luci-py: Making __file__ usage unicode safe.

client/tools/diff_isolates.py

 #!/usr/bin/env python
 # Copyright 2016 The LUCI 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.
 
 """Perform a recursive diff on two isolated file hashes."""
 
 import argparse
 import ast
 import os
 import json
 import shutil
 import subprocess
 import sys
 import tempfile
 
-CLIENT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+CLIENT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(
+    __file__.decode(sys.getfilesystemencoding()))))
 sys.path.insert(0, CLIENT_DIR)
 
 from utils import net
 
 
 def download_isolated_file(h, workdir, isolate_server, namespace):
   """Download the isolated file with the given hash and return its contents."""
   dst = os.path.join(workdir, h)
   if not os.path.isfile(dst):
     subprocess.check_call(['python', 'isolateserver.py', 'download',
@@ skipping 80 matching lines @@
   try:
     return diff_isolates(args.hash1, args.hash2, args.workdir, args.difftool,
                          args.isolate_server, args.namespace)
   finally:
     if using_tmp_dir:
       shutil.rmtree(args.workdir)
 
 
 if __name__ == '__main__':
   sys.exit(main())