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

client/tests/isolateserver_test.py

 #!/usr/bin/env python
 # Copyright 2013 The Swarming Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0 that
 # can be found in the LICENSE file.
 
 # pylint: disable=W0212,W0223,W0231,W0613
 
 import base64
 import hashlib
 import json
 import logging
 import os
 import StringIO
 import sys
 import tempfile
 import unittest
 import urllib
 import zlib
 
 # net_utils adjusts sys.path.
 import net_utils
 
 import auth
 import isolated_format
 import isolateserver
 import test_utils
 from depot_tools import auto_stub
+from depot_tools import fix_encoding
 from utils import file_path
 from utils import threading_utils
 
 import isolateserver_mock
 
 
 CONTENTS = {
   'empty_file.txt': '',
   'small_file.txt': 'small file\n',
   # TODO(maruel): symlinks.
@@ skipping 947 matching lines @@
     with test_utils.EnvVars({'ISOLATE_SERVER': 'https://localhost:1'}):
       self.help_test_archive(['archive'])
 
 
 def clear_env_vars():
   for e in ('ISOLATE_DEBUG', 'ISOLATE_SERVER'):
     os.environ.pop(e, None)
 
 
 if __name__ == '__main__':
+  fix_encoding.fix_encoding()
   if '-v' in sys.argv:
     unittest.TestCase.maxDiff = None
   logging.basicConfig(
       level=(logging.DEBUG if '-v' in sys.argv else logging.CRITICAL))
   clear_env_vars()
   unittest.main()