git-cl: Better warning message for legacy buckets.

Bug: 976104
Change-Id: Ide06f73faf7a9ce6aa2d7f47deffc0c505dcdb14
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1835017
Auto-Submit: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>
Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
diff --git a/tests/git_cl_test.py b/tests/git_cl_test.py
index d3b083e..5f191a1 100755
--- a/tests/git_cl_test.py
+++ b/tests/git_cl_test.py
@@ -3321,8 +3321,9 @@
       self.assertEqual(
           test_case['result'], git_cl._parse_bucket(test_case['bucket']))
       if test_case.get('has_warning'):
-        self.assertIn(
-            'WARNING Please specify buckets', git_cl.sys.stdout.getvalue())
+        expected_warning = 'WARNING Please use %s/%s to specify the bucket' % (
+            test_case['result'])
+        self.assertIn(expected_warning, git_cl.sys.stdout.getvalue())
 
 
 class CMDUploadTestCase(unittest.TestCase):