Use current issue number for git cl patch

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."""
 
 from distutils.version import LooseVersion
@@ skipping 2927 matching lines @@
   parser.add_option('-f', '--force', action='store_true',
                     help='with -b, clobber any existing branch')
   parser.add_option('-d', '--directory', action='store', metavar='DIR',
                     help='Change to the directory DIR immediately, '
                          'before doing anything else.')
   parser.add_option('--reject', action='store_true',
                     help='failed patches spew .rej files rather than '
                         'attempting a 3-way merge')
   parser.add_option('-n', '--no-commit', action='store_true', dest='nocommit',
                     help="don't commit after patch applies")
+
+  group = optparse.OptionGroup(parser,
+                    """Options for continuing work on the current issue uploaded
+from a different clone (e.g. different machine). Must be used independently from
+the other options. No issue number should be specified, and the branch must have
+an issue number associated with it""")
+  group.add_option('--reapply', action='store_true',
+                    dest='reapply',
+                    help="""Reset the branch and reapply the issue.
+CAUTION: This will undo any local changes in this branch""")
+
+  group.add_option('--pull', action='store_true', dest='pull',
+                    help="Performs a pull before reapplying.")
+  parser.add_option_group(group)
+
   auth.add_auth_options(parser)
   (options, args) = parser.parse_args(args)
   auth_config = auth.extract_auth_config_from_options(options)
 
-  if len(args) != 1:
-    parser.print_help()
-    return 1
+  issue_arg = None
+  if options.reapply :
+    if len(args) > 0:
+      parser.error("--reapply implies no additional arguments.")
 
-  issue_arg = ParseIssueNum(args[0])
+    cl = Changelist()
+    issue_arg = cl.GetIssue()
+    upstream = cl.GetUpstreamBranch()
+    if upstream == None:
+      parser.error("No upstream branch specified. Cannot reset branch")
+
+    RunGit(['reset', '--hard', upstream])
+    if options.pull:
+      RunGit(['pull'])
+  else:
+    if len(args) != 1:
+      parser.error("Must specify issue number")
+
+    issue_arg = ParseIssueNum(args[0])
+
   # The patch URL works because ParseIssueNum won't do any substitution
   # as the re.sub pattern fails to match and just returns it.
   if issue_arg == None:
     parser.print_help()
     return 1
 
   # We don't want uncommitted changes mixed up with the patch.
   if git_common.is_dirty_git_tree('patch'):
     return 1
 
   # TODO(maruel): Use apply_issue.py
   # TODO(ukai): use gerrit-cherry-pick for gerrit repository?
 
   if options.newbranch:
+    if options.reapply:
+      parser.error("--reapply excludes any option other than --pull")
     if options.force:
       RunGit(['branch', '-D', options.newbranch],
           stderr=subprocess2.PIPE, error_ok=True)
     RunGit(['checkout', '-b', options.newbranch,
             Changelist().GetUpstreamBranch()])
 
   return PatchIssue(issue_arg, options.reject, options.nocommit,
                     options.directory, auth_config)
 
 
@@ skipping 734 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()
   colorama.init()
   try:
     sys.exit(main(sys.argv[1:]))
   except KeyboardInterrupt:
     sys.stderr.write('interrupted\n')
     sys.exit(1)