[Android] Fix import error in browsertests/dispatch.py

build/android/pylib/browsertests/dispatch.py

 # Copyright (c) 2013 The Chromium 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 logging
 import os
 import sys
 
 from pylib import android_commands
 from pylib import cmd_helper
 from pylib import constants
 from pylib import ports
 from pylib.base import shard
 from pylib.gtest import dispatch as gtest_dispatch
 from pylib.gtest import test_runner
 from pylib.utils import report_results
 
-sys.path.append(os.path.join(constants.DIR_SOURCE_ROOT, 'build', 'util', 'lib'))
+sys.path.insert(0,
+                os.path.join(constants.DIR_SOURCE_ROOT, 'build', 'util', 'lib'))
 
 from common import unittest_util
 
 def Dispatch(options):
   attached_devices = []
   if options.test_device:
     attached_devices = [options.test_device]
   else:
     attached_devices = android_commands.GetAttachedDevices()
 
@@ skipping 60 matching lines @@
 def _ShouldRunOnBot(test):
   fixture, case = test.split('.', 1)
   if _StartsWith(fixture, case, "PRE_"):
     return False
   if _StartsWith(fixture, case, "MANUAL_"):
     return False
   return True
 
 def _StartsWith(a, b, prefix):
   return a.startswith(prefix) or b.startswith(prefix)