upload.py: honor explicit empty title

git_cl.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.
 
 # Copyright (C) 2008 Evan Martin <martine@danga.com>
 
 """A git-command for integrating reviews on Rietveld and Gerrit."""
 
 from __future__ import print_function
@@ skipping 1880 matching lines @@
     upload_args.extend(auth.auth_config_to_command_options(self._auth_config))
     if options.emulate_svn_auto_props:
       upload_args.append('--emulate_svn_auto_props')
 
     change_desc = None
 
     if options.email is not None:
       upload_args.extend(['--email', options.email])
 
     if self.GetIssue():
-      if options.title:
+      if options.title is not None:
         upload_args.extend(['--title', options.title])
       if options.message:
         upload_args.extend(['--message', options.message])
       upload_args.extend(['--issue', str(self.GetIssue())])
       print('This branch is associated with issue %s. '
             'Adding patch to that issue.' % self.GetIssue())
     else:
-      if options.title:
+      if options.title is not None:
         upload_args.extend(['--title', options.title])
       message = (options.title or options.message or
                  CreateDescriptionFromLog(args))
       change_desc = ChangeDescription(message)
       if options.reviewers or options.tbr_owners:
         change_desc.update_reviewers(options.reviewers,
                                      options.tbr_owners,
                                      change)
       if not options.force:
         change_desc.prompt()
@@ skipping 3159 matching lines @@
 if __name__ == '__main__':
   # These affect sys.stdout so do it outside of main() to simplify mocks in
   # unit testing.
   fix_encoding.fix_encoding()
   setup_color.init()
   try:
     sys.exit(main(sys.argv[1:]))
   except KeyboardInterrupt:
     sys.stderr.write('interrupted\n')
     sys.exit(1)