Fix progress check in auto-roller.

tools/release/auto_roll.py

 #!/usr/bin/env python
 # Copyright 2014 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import json
 import os
 import sys
 import urllib
@@ skipping 38 matching lines @@
     assert revisions, "Didn't find any recent release."
 
     # Interpret the DEPS file to retrieve the v8 revision.
     # TODO(machenbach): This should be part or the roll-deps api of
     # depot_tools.
     Var = lambda var: '%s'
     exec(FileToText(os.path.join(self._options.chromium, "DEPS")))
 
     # The revision rolled last.
     self["last_roll"] = vars['v8_revision']
+    last_version = self.GetVersionTag(self["last_roll"])
+    assert last_version, "The last rolled v8 revision is not tagged."
 
     # There must be some progress between the last roll and the new candidate
     # revision (i.e. we don't go backwards). The revisions are ordered newest
     # to oldest. It is possible that the newest timestamp has no progress
     # compared to the last roll, i.e. if the newest release is a cherry-pick
     # on a release branch. Then we look further.
     for revision in revisions:
-      commits = self.GitLog(
-        format="%H", git_hash="%s..%s" % (self["last_roll"], revision))
-      if commits:
+      version = self.GetVersionTag(revision)
+      assert version, "Internal error. All recent releases should have a tag"
+
+      if SortingKey(last_version) < SortingKey(version):
         self["roll"] = revision
         break
     else:
       print("There is no newer v8 revision than the one in Chromium (%s)."
             % self["last_roll"])
       return True
 
 
 class RollChromium(Step):
   MESSAGE = "Roll V8 into Chromium."
@@ skipping 44 matching lines @@
   def _Steps(self):
     return [
       CheckActiveRoll,
       DetectLastRoll,
       RollChromium,
     ]
 
 
 if __name__ == "__main__":  # pragma: no cover
   sys.exit(AutoRoll().Run())