diff --git a/pkg/model/resources/nodeup.go b/pkg/model/resources/nodeup.go
index 220caa0f99..5156741934 100644
--- a/pkg/model/resources/nodeup.go
+++ b/pkg/model/resources/nodeup.go
@@ -62,19 +62,15 @@ function ensure-install-dir() {
   cd ${INSTALL_DIR}
 }
 
-# Retry a download until we get it. Takes a hash and a set of URLs.
-#
-# $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-# $2+ are the URLs to download.
+# Retry a download until we get it. args: name, sha, url1, url2...
 download-or-bust() {
-  local -r hash="$1"
-  shift 1
+  local -r file="$1"
+  local -r hash="$2"
+  shift 2
 
   urls=( $* )
   while true; do
     for url in "${urls[@]}"; do
-      local file="${url##*/}"
-
       if [[ -e "${file}" ]]; then
         echo "== File exists for ${url} =="
 
@@ -132,18 +128,17 @@ function try-download-release() {
   # optimization.
 
   local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-  local -r nodeup_filename="${nodeup_urls[0]##*/}"
   if [[ -n "${NODEUP_HASH:-}" ]]; then
     local -r nodeup_hash="${NODEUP_HASH}"
   else
   # TODO: Remove?
     echo "Downloading sha1 (not found in env)"
-    download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-    local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+    download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+    local -r nodeup_hash=$(cat nodeup.sha1)
   fi
 
   echo "Downloading nodeup (${nodeup_urls[@]})"
-  download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+  download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
   chmod +x nodeup
 }
diff --git a/pkg/model/tests/data/bootstrapscript_0.txt b/pkg/model/tests/data/bootstrapscript_0.txt
index 4180abec73..5550ae8418 100644
--- a/pkg/model/tests/data/bootstrapscript_0.txt
+++ b/pkg/model/tests/data/bootstrapscript_0.txt
@@ -51,19 +51,15 @@ function ensure-install-dir() {
   cd ${INSTALL_DIR}
 }
 
-# Retry a download until we get it. Takes a hash and a set of URLs.
-#
-# $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-# $2+ are the URLs to download.
+# Retry a download until we get it. args: name, sha, url1, url2...
 download-or-bust() {
-  local -r hash="$1"
-  shift 1
+  local -r file="$1"
+  local -r hash="$2"
+  shift 2
 
   urls=( $* )
   while true; do
     for url in "${urls[@]}"; do
-      local file="${url##*/}"
-
       if [[ -e "${file}" ]]; then
         echo "== File exists for ${url} =="
 
@@ -121,18 +117,17 @@ function try-download-release() {
   # optimization.
 
   local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-  local -r nodeup_filename="${nodeup_urls[0]##*/}"
   if [[ -n "${NODEUP_HASH:-}" ]]; then
     local -r nodeup_hash="${NODEUP_HASH}"
   else
   # TODO: Remove?
     echo "Downloading sha1 (not found in env)"
-    download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-    local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+    download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+    local -r nodeup_hash=$(cat nodeup.sha1)
   fi
 
   echo "Downloading nodeup (${nodeup_urls[@]})"
-  download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+  download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
   chmod +x nodeup
 }
diff --git a/pkg/model/tests/data/bootstrapscript_1.txt b/pkg/model/tests/data/bootstrapscript_1.txt
index ba6d30087a..ef4e4f3625 100644
--- a/pkg/model/tests/data/bootstrapscript_1.txt
+++ b/pkg/model/tests/data/bootstrapscript_1.txt
@@ -51,19 +51,15 @@ function ensure-install-dir() {
   cd ${INSTALL_DIR}
 }
 
-# Retry a download until we get it. Takes a hash and a set of URLs.
-#
-# $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-# $2+ are the URLs to download.
+# Retry a download until we get it. args: name, sha, url1, url2...
 download-or-bust() {
-  local -r hash="$1"
-  shift 1
+  local -r file="$1"
+  local -r hash="$2"
+  shift 2
 
   urls=( $* )
   while true; do
     for url in "${urls[@]}"; do
-      local file="${url##*/}"
-
       if [[ -e "${file}" ]]; then
         echo "== File exists for ${url} =="
 
@@ -121,18 +117,17 @@ function try-download-release() {
   # optimization.
 
   local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-  local -r nodeup_filename="${nodeup_urls[0]##*/}"
   if [[ -n "${NODEUP_HASH:-}" ]]; then
     local -r nodeup_hash="${NODEUP_HASH}"
   else
   # TODO: Remove?
     echo "Downloading sha1 (not found in env)"
-    download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-    local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+    download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+    local -r nodeup_hash=$(cat nodeup.sha1)
   fi
 
   echo "Downloading nodeup (${nodeup_urls[@]})"
-  download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+  download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
   chmod +x nodeup
 }
diff --git a/pkg/model/tests/data/bootstrapscript_2.txt b/pkg/model/tests/data/bootstrapscript_2.txt
index ba6d30087a..ef4e4f3625 100644
--- a/pkg/model/tests/data/bootstrapscript_2.txt
+++ b/pkg/model/tests/data/bootstrapscript_2.txt
@@ -51,19 +51,15 @@ function ensure-install-dir() {
   cd ${INSTALL_DIR}
 }
 
-# Retry a download until we get it. Takes a hash and a set of URLs.
-#
-# $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-# $2+ are the URLs to download.
+# Retry a download until we get it. args: name, sha, url1, url2...
 download-or-bust() {
-  local -r hash="$1"
-  shift 1
+  local -r file="$1"
+  local -r hash="$2"
+  shift 2
 
   urls=( $* )
   while true; do
     for url in "${urls[@]}"; do
-      local file="${url##*/}"
-
       if [[ -e "${file}" ]]; then
         echo "== File exists for ${url} =="
 
@@ -121,18 +117,17 @@ function try-download-release() {
   # optimization.
 
   local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-  local -r nodeup_filename="${nodeup_urls[0]##*/}"
   if [[ -n "${NODEUP_HASH:-}" ]]; then
     local -r nodeup_hash="${NODEUP_HASH}"
   else
   # TODO: Remove?
     echo "Downloading sha1 (not found in env)"
-    download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-    local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+    download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+    local -r nodeup_hash=$(cat nodeup.sha1)
   fi
 
   echo "Downloading nodeup (${nodeup_urls[@]})"
-  download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+  download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
   chmod +x nodeup
 }
diff --git a/pkg/model/tests/data/bootstrapscript_3.txt b/pkg/model/tests/data/bootstrapscript_3.txt
index a7f0afb42d..8398ba69d9 100644
--- a/pkg/model/tests/data/bootstrapscript_3.txt
+++ b/pkg/model/tests/data/bootstrapscript_3.txt
@@ -51,19 +51,15 @@ function ensure-install-dir() {
   cd ${INSTALL_DIR}
 }
 
-# Retry a download until we get it. Takes a hash and a set of URLs.
-#
-# $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-# $2+ are the URLs to download.
+# Retry a download until we get it. args: name, sha, url1, url2...
 download-or-bust() {
-  local -r hash="$1"
-  shift 1
+  local -r file="$1"
+  local -r hash="$2"
+  shift 2
 
   urls=( $* )
   while true; do
     for url in "${urls[@]}"; do
-      local file="${url##*/}"
-
       if [[ -e "${file}" ]]; then
         echo "== File exists for ${url} =="
 
@@ -121,18 +117,17 @@ function try-download-release() {
   # optimization.
 
   local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-  local -r nodeup_filename="${nodeup_urls[0]##*/}"
   if [[ -n "${NODEUP_HASH:-}" ]]; then
     local -r nodeup_hash="${NODEUP_HASH}"
   else
   # TODO: Remove?
     echo "Downloading sha1 (not found in env)"
-    download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-    local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+    download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+    local -r nodeup_hash=$(cat nodeup.sha1)
   fi
 
   echo "Downloading nodeup (${nodeup_urls[@]})"
-  download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+  download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
   chmod +x nodeup
 }
diff --git a/pkg/model/tests/data/bootstrapscript_4.txt b/pkg/model/tests/data/bootstrapscript_4.txt
index 321560977b..69748f89ea 100644
--- a/pkg/model/tests/data/bootstrapscript_4.txt
+++ b/pkg/model/tests/data/bootstrapscript_4.txt
@@ -51,19 +51,15 @@ function ensure-install-dir() {
   cd ${INSTALL_DIR}
 }
 
-# Retry a download until we get it. Takes a hash and a set of URLs.
-#
-# $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-# $2+ are the URLs to download.
+# Retry a download until we get it. args: name, sha, url1, url2...
 download-or-bust() {
-  local -r hash="$1"
-  shift 1
+  local -r file="$1"
+  local -r hash="$2"
+  shift 2
 
   urls=( $* )
   while true; do
     for url in "${urls[@]}"; do
-      local file="${url##*/}"
-
       if [[ -e "${file}" ]]; then
         echo "== File exists for ${url} =="
 
@@ -121,18 +117,17 @@ function try-download-release() {
   # optimization.
 
   local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-  local -r nodeup_filename="${nodeup_urls[0]##*/}"
   if [[ -n "${NODEUP_HASH:-}" ]]; then
     local -r nodeup_hash="${NODEUP_HASH}"
   else
   # TODO: Remove?
     echo "Downloading sha1 (not found in env)"
-    download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-    local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+    download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+    local -r nodeup_hash=$(cat nodeup.sha1)
   fi
 
   echo "Downloading nodeup (${nodeup_urls[@]})"
-  download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+  download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
   chmod +x nodeup
 }
diff --git a/pkg/model/tests/data/bootstrapscript_5.txt b/pkg/model/tests/data/bootstrapscript_5.txt
index 321560977b..69748f89ea 100644
--- a/pkg/model/tests/data/bootstrapscript_5.txt
+++ b/pkg/model/tests/data/bootstrapscript_5.txt
@@ -51,19 +51,15 @@ function ensure-install-dir() {
   cd ${INSTALL_DIR}
 }
 
-# Retry a download until we get it. Takes a hash and a set of URLs.
-#
-# $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-# $2+ are the URLs to download.
+# Retry a download until we get it. args: name, sha, url1, url2...
 download-or-bust() {
-  local -r hash="$1"
-  shift 1
+  local -r file="$1"
+  local -r hash="$2"
+  shift 2
 
   urls=( $* )
   while true; do
     for url in "${urls[@]}"; do
-      local file="${url##*/}"
-
       if [[ -e "${file}" ]]; then
         echo "== File exists for ${url} =="
 
@@ -121,18 +117,17 @@ function try-download-release() {
   # optimization.
 
   local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-  local -r nodeup_filename="${nodeup_urls[0]##*/}"
   if [[ -n "${NODEUP_HASH:-}" ]]; then
     local -r nodeup_hash="${NODEUP_HASH}"
   else
   # TODO: Remove?
     echo "Downloading sha1 (not found in env)"
-    download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-    local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+    download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+    local -r nodeup_hash=$(cat nodeup.sha1)
   fi
 
   echo "Downloading nodeup (${nodeup_urls[@]})"
-  download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+  download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
   chmod +x nodeup
 }
diff --git a/tests/integration/update_cluster/additional_cidr/cloudformation.json.extracted.yaml b/tests/integration/update_cluster/additional_cidr/cloudformation.json.extracted.yaml
index 9b088d27dd..d1e10dea5a 100644
--- a/tests/integration/update_cluster/additional_cidr/cloudformation.json.extracted.yaml
+++ b/tests/integration/update_cluster/additional_cidr/cloudformation.json.extracted.yaml
@@ -36,19 +36,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1bmastersadditionalcidrex
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -106,18 +102,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1bmastersadditionalcidrex
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -315,19 +310,15 @@ Resources.AWSAutoScalingLaunchConfigurationnodesadditionalcidrexamplecom.Propert
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -385,18 +376,17 @@ Resources.AWSAutoScalingLaunchConfigurationnodesadditionalcidrexamplecom.Propert
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
diff --git a/tests/integration/update_cluster/additional_user-data/cloudformation.json.extracted.yaml b/tests/integration/update_cluster/additional_user-data/cloudformation.json.extracted.yaml
index b927c30744..06dd04d510 100644
--- a/tests/integration/update_cluster/additional_user-data/cloudformation.json.extracted.yaml
+++ b/tests/integration/update_cluster/additional_user-data/cloudformation.json.extracted.yaml
@@ -45,19 +45,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersadditionaluserda
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -115,18 +111,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersadditionaluserda
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -344,19 +339,15 @@ Resources.AWSAutoScalingLaunchConfigurationnodesadditionaluserdataexamplecom.Pro
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -414,18 +405,17 @@ Resources.AWSAutoScalingLaunchConfigurationnodesadditionaluserdataexamplecom.Pro
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
diff --git a/tests/integration/update_cluster/existing_iam_cloudformation/cloudformation.json.extracted.yaml b/tests/integration/update_cluster/existing_iam_cloudformation/cloudformation.json.extracted.yaml
index d51e63c06f..77916aa3a4 100644
--- a/tests/integration/update_cluster/existing_iam_cloudformation/cloudformation.json.extracted.yaml
+++ b/tests/integration/update_cluster/existing_iam_cloudformation/cloudformation.json.extracted.yaml
@@ -36,19 +36,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersminimalexampleco
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -106,18 +102,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersminimalexampleco
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -315,19 +310,15 @@ Resources.AWSAutoScalingLaunchConfigurationnodesminimalexamplecom.Properties.Use
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -385,18 +376,17 @@ Resources.AWSAutoScalingLaunchConfigurationnodesminimalexamplecom.Properties.Use
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
diff --git a/tests/integration/update_cluster/externallb/cloudformation.json.extracted.yaml b/tests/integration/update_cluster/externallb/cloudformation.json.extracted.yaml
index aa708175f7..06075b930b 100644
--- a/tests/integration/update_cluster/externallb/cloudformation.json.extracted.yaml
+++ b/tests/integration/update_cluster/externallb/cloudformation.json.extracted.yaml
@@ -36,19 +36,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersexternallbexampl
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -106,18 +102,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersexternallbexampl
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -335,19 +330,15 @@ Resources.AWSAutoScalingLaunchConfigurationnodesexternallbexamplecom.Properties.
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -405,18 +396,17 @@ Resources.AWSAutoScalingLaunchConfigurationnodesexternallbexamplecom.Properties.
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
diff --git a/tests/integration/update_cluster/minimal-cloudformation/cloudformation.json.extracted.yaml b/tests/integration/update_cluster/minimal-cloudformation/cloudformation.json.extracted.yaml
index d51e63c06f..77916aa3a4 100644
--- a/tests/integration/update_cluster/minimal-cloudformation/cloudformation.json.extracted.yaml
+++ b/tests/integration/update_cluster/minimal-cloudformation/cloudformation.json.extracted.yaml
@@ -36,19 +36,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersminimalexampleco
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -106,18 +102,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersminimalexampleco
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -315,19 +310,15 @@ Resources.AWSAutoScalingLaunchConfigurationnodesminimalexamplecom.Properties.Use
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -385,18 +376,17 @@ Resources.AWSAutoScalingLaunchConfigurationnodesminimalexamplecom.Properties.Use
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
diff --git a/tests/integration/update_cluster/mixed_instances/cloudformation.json.extracted.yaml b/tests/integration/update_cluster/mixed_instances/cloudformation.json.extracted.yaml
index bb46a9c356..0163572745 100644
--- a/tests/integration/update_cluster/mixed_instances/cloudformation.json.extracted.yaml
+++ b/tests/integration/update_cluster/mixed_instances/cloudformation.json.extracted.yaml
@@ -36,19 +36,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersmixedinstancesex
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -106,18 +102,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersmixedinstancesex
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -336,19 +331,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1bmastersmixedinstancesex
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -406,18 +397,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1bmastersmixedinstancesex
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -636,19 +626,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1cmastersmixedinstancesex
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -706,18 +692,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1cmastersmixedinstancesex
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -936,19 +921,15 @@ Resources.AWSEC2LaunchTemplatenodesmixedinstancesexamplecom.Properties.LaunchTem
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -1006,18 +987,17 @@ Resources.AWSEC2LaunchTemplatenodesmixedinstancesexamplecom.Properties.LaunchTem
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
diff --git a/tests/integration/update_cluster/mixed_instances_spot/cloudformation.json.extracted.yaml b/tests/integration/update_cluster/mixed_instances_spot/cloudformation.json.extracted.yaml
index bb46a9c356..0163572745 100644
--- a/tests/integration/update_cluster/mixed_instances_spot/cloudformation.json.extracted.yaml
+++ b/tests/integration/update_cluster/mixed_instances_spot/cloudformation.json.extracted.yaml
@@ -36,19 +36,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersmixedinstancesex
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -106,18 +102,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1amastersmixedinstancesex
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -336,19 +331,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1bmastersmixedinstancesex
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -406,18 +397,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1bmastersmixedinstancesex
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -636,19 +626,15 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1cmastersmixedinstancesex
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -706,18 +692,17 @@ Resources.AWSAutoScalingLaunchConfigurationmasterustest1cmastersmixedinstancesex
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }
@@ -936,19 +921,15 @@ Resources.AWSEC2LaunchTemplatenodesmixedinstancesexamplecom.Properties.LaunchTem
     cd ${INSTALL_DIR}
   }
 
-  # Retry a download until we get it. Takes a hash and a set of URLs.
-  #
-  # $1 is the sha1 of the URL. Can be "" if the sha1 is unknown.
-  # $2+ are the URLs to download.
+  # Retry a download until we get it. args: name, sha, url1, url2...
   download-or-bust() {
-    local -r hash="$1"
-    shift 1
+    local -r file="$1"
+    local -r hash="$2"
+    shift 2
 
     urls=( $* )
     while true; do
       for url in "${urls[@]}"; do
-        local file="${url##*/}"
-
         if [[ -e "${file}" ]]; then
           echo "== File exists for ${url} =="
 
@@ -1006,18 +987,17 @@ Resources.AWSEC2LaunchTemplatenodesmixedinstancesexamplecom.Properties.LaunchTem
     # optimization.
 
     local -r nodeup_urls=( $(split-commas "${NODEUP_URL}") )
-    local -r nodeup_filename="${nodeup_urls[0]##*/}"
     if [[ -n "${NODEUP_HASH:-}" ]]; then
       local -r nodeup_hash="${NODEUP_HASH}"
     else
     # TODO: Remove?
       echo "Downloading sha1 (not found in env)"
-      download-or-bust "" "${nodeup_urls[@]/%/.sha1}"
-      local -r nodeup_hash=$(cat "${nodeup_filename}.sha1")
+      download-or-bust nodeup.sha1 "" "${nodeup_urls[@]/%/.sha1}"
+      local -r nodeup_hash=$(cat nodeup.sha1)
     fi
 
     echo "Downloading nodeup (${nodeup_urls[@]})"
-    download-or-bust "${nodeup_hash}" "${nodeup_urls[@]}"
+    download-or-bust nodeup "${nodeup_hash}" "${nodeup_urls[@]}"
 
     chmod +x nodeup
   }