Added message when upstream branch is gone.

BUG=496892

Review URL: https://codereview.chromium.org/1156223008

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@295634 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/tests/git_cl_test.py b/tests/git_cl_test.py
index cb87bdb..b19e45c 100755
--- a/tests/git_cl_test.py
+++ b/tests/git_cl_test.py
@@ -86,6 +86,7 @@
     self.mock(git_common, 'get_or_create_merge_base',
               lambda *a: (
                   self._mocked_call(['get_or_create_merge_base']+list(a))))
+    self.mock(git_cl, 'BranchExists', lambda _: True)
     self.mock(git_cl, 'FindCodereviewSettingsFile', lambda: '')
     self.mock(git_cl, 'ask_for_data', self._mocked_call)
     self.mock(git_cl.breakpad, 'post', self._mocked_call)