Add tag write access to merge script.

tools/push-to-trunk/common_includes.py

 #!/usr/bin/env python
 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
@@ skipping 328 matching lines @@
   def Land(self):
     self.step.GitSVNDCommit()
 
   def CLLand(self):
     self.step.GitDCommit()
 
   def Tag(self, tag):
     self.step.GitSVNTag(tag)
 
 
-class GitReadOnlyMixin(VCInterface):
+class GitTagsOnlyMixin(VCInterface):
   def Pull(self):
     self.step.GitPull()
 
   def Fetch(self):
     self.step.Git("fetch")
 
   def GetTags(self):
      return self.step.Git("tag").strip().splitlines()
 
   def GetBranches(self):
     # Get relevant remote branches, e.g. "origin/branch-heads/3.25".
     branches = filter(
         lambda s: re.match(r"^origin/branch\-heads/\d+\.\d+$", s),
         self.step.GitRemotes())
     # Remove 'origin/branch-heads/' prefix.
     return map(lambda s: s[20:], branches)
 
   def RemoteMasterBranch(self):
     return "origin/master"
 
   def RemoteCandidateBranch(self):
     return "origin/candidates"
 
   def RemoteBranch(self, name):
     if name in ["candidates", "master"]:
       return "origin/%s" % name
     return "origin/branch-heads/%s" % name
 
+  def Tag(self, tag):
+    self.step.Git("tag %s" % tag)
+    self.step.Git("push origin %s" % tag)
 
-class GitReadSvnWriteInterface(GitReadOnlyMixin, GitSvnInterface):
+
+class GitReadSvnWriteInterface(GitTagsOnlyMixin, GitSvnInterface):
   pass
 
 
 VC_INTERFACES = {
   "git_svn": GitSvnInterface,
   "git_read_svn_write": GitReadSvnWriteInterface,
 }
 
 
 class Step(GitRecipesMixin):
@@ skipping 446 matching lines @@
     for (number, step_class) in enumerate(step_classes):
       steps.append(MakeStep(step_class, number, self._state, self._config,
                             options, self._side_effect_handler))
     for step in steps[options.step:]:
       if step.Run():
         return 0
     return 0
 
   def Run(self, args=None):
     return self.RunSteps(self._Steps(), args)