Indiciate the tree status in the rietveld message when bypassing hooks

tests/git_cl_test.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Unit tests for git_cl.py."""
 
 import os
 import StringIO
 import stat
@@ skipping 293 matching lines @@
       ((['git', 'config', 'rietveld.tree-status-url'],), ''),
   ]
 
   @classmethod
   def _dcommit_calls_bypassed(cls):
     return [
       ((['git',
          'config', 'branch.working.rietveldissue'],), '12345'),
       ((['git', 'config', 'branch.working.rietveldserver'],),
          'codereview.example.com'),
+      ((['git', 'config', 'rietveld.tree-status-url'],), ''),
       (('GitClHooksBypassedCommit',
         'Issue https://codereview.example.com/12345 bypassed hook when '
-        'committing'), None),
+        'committing (tree status was "unset")'), None),
   ]
 
   @classmethod
   def _dcommit_calls_3(cls):
     return [
       ((['git',
          'diff', '--no-ext-diff', '--stat', '--find-copies-harder',
          '-l100000', '-C50', 'fake_ancestor_sha',
          'refs/heads/working'],),
        (' PRESUBMIT.py |    2 +-\n'
@@ skipping 400 matching lines @@
       obj = git_cl.ChangeDescription(orig)
       obj.update_reviewers(reviewers)
       actual.append(obj.description)
     self.assertEqual(expected, actual)
 
 
 if __name__ == '__main__':
   git_cl.logging.basicConfig(
       level=git_cl.logging.DEBUG if '-v' in sys.argv else git_cl.logging.ERROR)
   unittest.main()