git-cl: Print Rietveld deprecation warning

To encourage folks to upload to Gerrit.

Bug: 685321
Change-Id: I849ed53f95a2205959237fe825ffe41e349ff8c7
Reviewed-on: https://chromium-review.googlesource.com/510963
Reviewed-by: Andrew Bonventre <andybons@chromium.org>
Commit-Queue: Aaron Gable <agable@chromium.org>
diff --git a/tests/git_cl_test.py b/tests/git_cl_test.py
index e9ceb3d..570c3ab 100755
--- a/tests/git_cl_test.py
+++ b/tests/git_cl_test.py
@@ -982,7 +982,15 @@
     self.mock(sys, 'stdout', stdout)
     with self.assertRaises(SystemExitMock):
       git_cl.main(['upload', '--send-mail'])
-    self.assertEqual('', stdout.getvalue())
+    self.assertEqual(
+        '=====================================\n'
+        'NOTICE: Rietveld is being deprecated. '
+        'You can upload changes to Gerrit with\n'
+        '  git cl upload --gerrit\n'
+        'or set Gerrit to be your default code review tool with\n'
+        '  git config gerrit.host true\n'
+        '=====================================\n',
+        stdout.getvalue())
 
   def test_bug_on_cmd(self):
     self._run_reviewer_test(