Enforce workdir presence and add a README file in it to explain what needs to be done.

commit_queue.py

 #!/usr/bin/python
 # Copyright (c) 2010 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.
 """Commit queue executable.
 
 Reuse Rietveld and the Chromium Try Server to process and automatically commit
 patches.
 """
 
@@ skipping 54 matching lines @@
     parser.error('Need to pass a valid project to --project.\nOptions are: %s' %
         ', '.join(project_choices))
   if options.verbose:
     level = logging.DEBUG
   else:
     level = logging.INFO
   logging.basicConfig(
       level=level,
       format='%(asctime)s %(levelname)7s %(message)s')
   root_dir = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'workdir')
-  if not os.path.isdir(root_dir):
-    os.makedirs(root_dir)
-
-  gaia_creds = creds.Credentials(os.path.join(root_dir, '.gaia_pwd'))
+  gaia_file = os.path.join(root_dir, '.gaia_pwd')
+  if not os.path.isfile(gaia_file):
+    parser.error('Please read workdir/README.')
+  gaia_creds = creds.Credentials(gaia_file)
   rietveld_obj = rietveld.Rietveld(
       'http://codereview.chromium.org',
       'commit-bot@chromium.org',
       gaia_creds.get('commit-bot@chromium.org'))
   pc = projects.load_project(options.project, root_dir, rietveld_obj,
       options.git_svn, options.no_try)
 
   if options.dry_run:
     pc.checkout = checkout.ReadOnlyCheckout(pc.checkout)
 
@@ skipping 25 matching lines @@
           logging.info('Next poll in %1.1f second(s)' % delay)
           time.sleep(delay)
       last_loop = time.time()
   finally:
     pc.save(db_path)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())