Handle when a patchset doesn't exist instead of printing a stack trace.

apply_issue.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.
 
 """Applies an issue from Rietveld.
 """
 
 import logging
 import optparse
 import os
 import sys
+import urllib2
 
 import breakpad  # pylint: disable=W0611
 
 import checkout
 import fix_encoding
 import rietveld
 import scm
 
 
 def main():
@@ skipping 21 matching lines @@
       help='Rietveld server')
   options, args = parser.parse_args()
   logging.basicConfig(
       format='%(levelname)5s %(module)11s(%(lineno)4d): %(message)s',
       level=[logging.WARNING, logging.INFO, logging.DEBUG][
           min(2, options.verbose)])
   if args:
     parser.error('Extra argument(s) "%s" not understood' % ' '.join(args))
   if not options.issue:
     parser.error('Require --issue')
+  options.server = options.server.rstrip('/')
+  if not options.server:
+    parser.error('Require a valid server')
 
   # TODO(rogerta): Remove me, it's ugly.
   if options.email == '=':
     options.email = ''
 
   obj = rietveld.Rietveld(options.server, options.email, None)
 
   if not options.patchset:
     options.patchset = obj.get_issue_properties(
         options.issue, False)['patchsets'][-1]
     print('No patchset specified. Using patchset %d' % options.patchset)
 
   print('Downloading the patch.')
-  patchset = obj.get_patch(options.issue, options.patchset)
+  try:
+    patchset = obj.get_patch(options.issue, options.patchset)
+  except urllib2.HTTPError, e:
+    print >> sys.stderr, (
+        'Failed to fetch the patch for issue %d, patchset %d.\n'
+        'Try visiting %s/%d') % (
+            options.issue, options.patchset,
+            options.server, options.issue)
+    return 1
   for patch in patchset.patches:
     print(patch)
   scm_type = scm.determine_scm(options.root_dir)
   if scm_type == 'svn':
     scm_obj = checkout.SvnCheckout(options.root_dir, None, None, None, None)
   elif scm_type == 'git':
     scm_obj = checkout.GitCheckoutBase(options.root_dir, None, None)
   elif scm_type == None:
     scm_obj = checkout.RawCheckout(options.root_dir, None)
   else:
     parser.error('Couldn\'t determine the scm')
 
   # Apply the patch.
   try:
     scm_obj.apply_patch(patchset)
   except checkout.PatchApplicationFailed, e:
     print >> sys.stderr, str(e)
     return 1
   return 0
 
 
 if __name__ == "__main__":
   fix_encoding.fix_encoding()
   sys.exit(main())