SA: Fix NewOrder ready status regression.

In #3614 we adjusted the `SA.NewOrder` function to conditionally call
`ssa.statusForOrder` on the new order when `features.OrderReadyStatus`
was enabled. Unfortunately this call to `ssa.statusForOrder` happened
*before* the `req.BeganProcessing` field was initialized with a pointer
to a `false` bool. The `ssa.statusForOrder` function (correctly) assumes
that `req.BeganProcessing == nil` is illegal and doesn't correspond to
a known status. This results in NewOrder requests returning a 500 error
of the form:
> Internal error - Error creating new order - Order XXX is in an invalid
> state. No state known for this order's authorizations

Our integration tests missed this because we didn't have a test case
that issued for a set of names with one account, and then issued again
for the same set of names with the same account.

This commit fixes the original bug by moving the `BeganProcessing`
initialization before the call to `statusForOrder`. This commit also
adds an integration test to catch this sort of bug again in the
future.

Prior to the SA fix this test failed with the 500 server internal error
observed by the Certbot team. With the SA fix in place the test passes
again.

sa/sa.go

@@ -1460,6 +1460,9 @@ func (ssa *SQLStorageAuthority) NewOrder(ctx context.Context, req *corepb.Order)
 	// Update the request with the created timestamp from the model
 	createdTS := order.Created.UnixNano()
 	req.Created = &createdTS
+	// A new order is never processing because it can't have been finalized yet
+	processingStatus := false
+	req.BeganProcessing = &processingStatus
 
 	// If the OrderReadyStatus feature is enabled we need to calculate the order
 	// status before returning it. Since it may have reused all valid
@@ -1478,9 +1481,6 @@ func (ssa *SQLStorageAuthority) NewOrder(ctx context.Context, req *corepb.Order)
 		pendingStatus := string(core.StatusPending)
 		req.Status = &pendingStatus
 	}
-	// A new order is never processing because it can't have been finalized yet
-	processingStatus := false
-	req.BeganProcessing = &processingStatus
 	// Return the new order
 	return req, nil
 }

test/v2_integration.py

@@ -115,6 +115,16 @@ def test_bad_overlap_wildcard():
     chisel2.expect_problem("urn:ietf:params:acme:error:malformed",
         lambda: chisel2.auth_and_issue(["*.example.com", "www.example.com"]))
 
+def test_duplicate_orders():
+    """
+    Test that the same client issuing for the same domain names twice in a row
+    works without error.
+    """
+    client = chisel2.make_client(None)
+    domains = [ random_domain() ]
+    chisel2.auth_and_issue(domains, client=client)
+    chisel2.auth_and_issue(domains, client=client)
+
 def test_order_reuse_failed_authz():
     """
     Test that creating an order for a domain name, failing an authorization in