Print failure reason when git cl try can't trigger jobs on a CL.

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 4781 matching lines @@
     parser.error('Need to upload first')
 
   if cl.IsGerrit():
     parser.error(
         'Not yet supported for Gerrit (http://crbug.com/599931).\n'
         'If your project has Commit Queue, dry run is a workaround:\n'
         '  git cl set-commit --dry-run')
 
   error_message = cl.CannotTriggerTryJobReason()
   if error_message:
-    parser.error('Can\'t trigger try jobs: %s')
+    parser.error('Can\'t trigger try jobs: %s' % error_message)
 
   if not options.name:
     options.name = cl.GetBranch()
 
   if options.bucket and options.master:
     parser.error('Only one of --bucket and --master may be used.')
 
   if options.bot and not options.master and not options.bucket:
     options.master, err_msg = GetBuilderMaster(options.bot)
     if err_msg:
@@ skipping 601 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)