Add an assert to ensure UTF-8 locale when handling file paths.

appengine/swarming/swarming_bot/bot_code/task_runner_test.py

 #!/usr/bin/env python
 # coding=utf-8
 # Copyright 2013 The Swarming Authors. All rights reserved.
 # Use of this source code is governed by the Apache v2.0 license that can be
 # found in the LICENSE file.
 
 import StringIO
 import base64
 import json
 import logging
 import os
 import signal
 import shutil
 import sys
 import tempfile
 import time
 import unittest
 import zipfile
 
 import test_env_bot_code
 test_env_bot_code.setup_test_env()
 
 # Creates a server mock for functions in net.py.
 import net_utils
 
+from depot_tools import fix_encoding
 from utils import file_path
 from utils import logging_utils
 from utils import subprocess42
 from utils import tools
 import fake_swarming
 import task_runner
 import xsrf_client
 
 
 def compress_to_zip(files):
@@ skipping 972 matching lines @@
       u'must_signal_internal_failure':
           u'task_runner received signal %d' % task_runner.SIG_BREAK_OR_TERM,
       u'version': 3,
     }
     with open(task_result_file, 'rb') as f:
       self.assertEqual(expected, json.load(f))
     self.assertEqual(0, proc.returncode)
 
 
 if __name__ == '__main__':
+  fix_encoding.fix_encoding()
   if '-v' in sys.argv:
     unittest.TestCase.maxDiff = None
   logging_utils.prepare_logging(None)
   logging_utils.set_console_level(
       logging.DEBUG if '-v' in sys.argv else logging.CRITICAL+1)
   # Fix litteral text expectation.
   os.environ['LANG'] = 'en_US.UTF-8'
   os.environ['LANGUAGE'] = 'en_US.UTF-8'
   unittest.main()