Fix clusterfuzz check in auto-roll.

tools/push-to-trunk/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 62 matching lines @@
 
   def RunStep(self):
     if not os.path.exists(self.Config(CLUSTERFUZZ_API_KEY_FILE)):
       print "Skipping ClusterFuzz check. No api key file found."
       return False
     api_key = FileToText(self.Config(CLUSTERFUZZ_API_KEY_FILE))
     # Check for open, reproducible issues that have no associated bug.
     result = self._side_effect_handler.ReadClusterFuzzAPI(
         api_key, job_type="linux_asan_d8_dbg", reproducible="True",
         open="True", bug_information="",
-        revision_greater_or_equal=self["last_push"])
+        revision_greater_or_equal=str(self["last_push"]))
     if result:
       print "Stop due to pending ClusterFuzz issues."
       return True
 
 
 class RollChromium(Step):
   MESSAGE = "Roll V8 into Chromium."
 
   def RunStep(self):
     if self._options.roll:
@@ skipping 36 matching lines @@
       CheckActiveRoll,
       DetectLastPush,
       DetectLastRoll,
       CheckClusterFuzz,
       RollChromium,
     ]
 
 
 if __name__ == "__main__":  # pragma: no cover
   sys.exit(AutoRoll(CONFIG).Run())