[release-tools] Fix possible race condition in retrieval of latest rolled version

tools/release/test_scripts.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 1094 matching lines @@
     self.Expect([
       URL("https://codereview.chromium.org/search",
           "owner=author%40chromium.org&limit=30&closed=3&format=json",
           ("{\"results\": [{\"subject\": \"different\"}]}")),
       Cmd("git fetch origin +refs/tags/*:refs/tags/*", ""),
       Cmd("git rev-list --max-age=740800 --tags",
           "bad_tag\nhash_234\nhash_123"),
       Cmd("git describe --tags bad_tag", ""),
       Cmd("git describe --tags hash_234", "3.22.4"),
       Cmd("git describe --tags hash_123", "3.22.3"),
+      Cmd("git pull", "", cwd=TEST_CONFIG["CHROMIUM"]),
       Cmd("git describe --tags abcd123455", "3.22.4"),
       Cmd("git describe --tags hash_234", "3.22.4"),
       Cmd("git describe --tags hash_123", "3.22.3"),
     ])
 
     result = auto_roll.AutoRoll(TEST_CONFIG, self).Run(
         AUTO_PUSH_ARGS + ["-c", TEST_CONFIG["CHROMIUM"]])
     self.assertEquals(0, result)
 
   def testAutoRoll(self):
     TEST_CONFIG["CHROMIUM"] = self.MakeEmptyTempDirectory()
     TextToFile(self.FAKE_DEPS, os.path.join(TEST_CONFIG["CHROMIUM"], "DEPS"))
 
     self.Expect([
       URL("https://codereview.chromium.org/search",
           "owner=author%40chromium.org&limit=30&closed=3&format=json",
           ("{\"results\": [{\"subject\": \"different\"}]}")),
       Cmd("git fetch origin +refs/tags/*:refs/tags/*", ""),
       Cmd("git rev-list --max-age=740800 --tags",
           "bad_tag\nhash_234\nhash_123"),
       Cmd("git describe --tags bad_tag", ""),
       Cmd("git describe --tags hash_234", "3.22.4"),
       Cmd("git describe --tags hash_123", "3.22.3"),
+      Cmd("git pull", "", cwd=TEST_CONFIG["CHROMIUM"]),
       Cmd("git describe --tags abcd123455", "3.22.3.1"),
       Cmd("git describe --tags hash_234", "3.22.4"),
     ])
 
     result = auto_roll.AutoRoll(TEST_CONFIG, self).Run(
         AUTO_PUSH_ARGS + ["-c", TEST_CONFIG["CHROMIUM"], "--roll"])
     self.assertEquals(0, result)
 
   def testMergeToBranch(self):
     TEST_CONFIG["ALREADY_MERGING_SENTINEL_FILE"] = self.MakeEmptyTempFile()
@@ skipping 395 matching lines @@
 
 Review URL: https://codereview.chromium.org/83173002
 
 ------------------------------------------------------------------------""")
     self.assertEquals(
 """Prepare push to trunk.  Now working on version 3.23.11.
 
 R=danno@chromium.org
 
 Committed: https://code.google.com/p/v8/source/detail?r=17997""", body)