Make git cl format work on my Windows box.

git_cl.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 # Copyright (C) 2008 Evan Martin <martine@danga.com>
 
 """A git-command for integrating reviews on Rietveld."""
 
 from distutils.version import LooseVersion
@@ skipping 2735 matching lines @@
       print "Nothing to format."
       return 0
     cmd = [clang_format_tool]
     if not opts.dry_run and not opts.diff:
       cmd.append('-i')
     stdout = RunCommand(cmd + files, cwd=top_dir)
     if opts.diff:
       sys.stdout.write(stdout)
   else:
     env = os.environ.copy()
-    env['PATH'] = os.path.dirname(clang_format_tool)
+    env['PATH'] = str(os.path.dirname(clang_format_tool))
     # diff_output is a patch to send to clang-format-diff.py
     try:
       script = clang_format.FindClangFormatScriptInChromiumTree(
           'clang-format-diff.py')
     except clang_format.NotFoundError, e:
       DieWithError(e)
 
     cmd = [sys.executable, script, '-p0']
     if not opts.dry_run and not opts.diff:
       cmd.append('-i')
@@ skipping 45 matching lines @@
         ('AppEngine is misbehaving and returned HTTP %d, again. Keep faith '
           'and retry or visit go/isgaeup.\n%s') % (e.code, str(e)))
 
 
 if __name__ == '__main__':
   # These affect sys.stdout so do it outside of main() to simplify mocks in
   # unit testing.
   fix_encoding.fix_encoding()
   colorama.init()
   sys.exit(main(sys.argv[1:]))