Add retry feature for push-to-trunk script.

tools/push-to-trunk/auto_roll.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 44 matching lines @@
     if not match:
       self.Die("Could not extract current svn revision from log.")
     self.Persist("latest", match.group(1))
 
 
 class FetchLKGR(Step):
   MESSAGE = "Fetching V8 LKGR."
 
   def RunStep(self):
     lkgr_url = "https://v8-status.appspot.com/lkgr"
-    self.Persist("lkgr", self.ReadURL(lkgr_url))
+    # Retry several times since app engine might have issues.
+    self.Persist("lkgr", self.ReadURL(lkgr_url, wait_plan=[5, 20, 20, 20]))
 
 
 class PushToTrunk(Step):
   MESSAGE = "Pushing to trunk if possible."
 
   def RunStep(self):
     self.RestoreIfUnset("latest")
     self.RestoreIfUnset("lkgr")
     latest = int(self._state["latest"])
     lkgr = int(self._state["lkgr"])
@@ skipping 25 matching lines @@
   return result
 
 
 def Main():
   parser = BuildOptions()
   (options, args) = parser.parse_args()
   RunAutoRoll(CONFIG, options)
 
 if __name__ == "__main__":
   sys.exit(Main())