git-cl-upload: warn if no rietveld project specified

Bug: 600469
Change-Id: I4ebc7b0f28204ae4a4649e51d6aac8fc2f43ed20
Reviewed-on: https://chromium-review.googlesource.com/556152
Reviewed-by: Andrew Bonventre <andybons@chromium.org>
Commit-Queue: Aaron Gable <agable@chromium.org>

git_cl.py

@@ -2311,6 +2311,11 @@ class _RietveldChangelistImpl(_ChangelistCodereviewBase):
     project = settings.GetProject()
     if project:
       upload_args.extend(['--project', project])
+    else:
+      print()
+      print('WARNING: Uploading without a project specified. Please ensure '
+            'your repo\'s codereview.settings has a "PROJECT: foo" line.')
+      print()
 
     try:
       upload_args = ['upload'] + upload_args + args