Don't clear up the Discourse env, we need it

lib/docker_manager/upgrader.rb

@@ -38,7 +38,12 @@ class DockerManager::Upgrader
   def run(cmd)
     log "$ #{cmd}"
     msg = ""
-    clear_env = Hash[*ENV.map{|k,v| [k,nil]}.reject{|k,v| ["REDIS_PROVIDER_URL","PWD","HOME","SHELL","PATH"].include?(k)}.flatten]
+    clear_env = Hash[*ENV.map{|k,v| [k,nil]}
+                     .reject{ |k,v|
+                       ["PWD","HOME","SHELL","PATH"].include?(k) ||
+                         k =~ /^DISCOURSE_/
+                     }
+                     .flatten]
     clear_env["RAILS_ENV"] = "production"
 
     IO.popen(clear_env, "cd #{Rails.root} && #{cmd} 2>&1") do |line|