chromevox: Fix a racy failure in directory creation in jsbundler.py.

chrome/browser/resources/chromeos/chromevox/tools/jsbundler.py

 #!/usr/bin/env python
 
 # Copyright 2014 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.
 
 '''Produces various output formats from a set of JavaScript files with
 closure style require/provide calls.
 
 Scans one or more directory trees for JavaScript files.  Then, from a
@@ skipping 12 matching lines @@
 - bundle: a concatenation of all the files, separated by newlines is output.
 
 - compressed_bundle: A bundle where non-significant whitespace, including
   comments, has been stripped is output.
 
 - copy: the files are copied, or hard linked if possible, to the destination
   directory.  In this case, no output is generated.
 '''
 
 
+import errno
 import optparse
 import os
 import re
 import shutil
 import sys
 
 _SCRIPT_DIR = os.path.realpath(os.path.dirname(__file__))
 _CHROME_SOURCE = os.path.realpath(
     os.path.join(_SCRIPT_DIR, *[os.path.pardir] * 6))
 sys.path.insert(0, os.path.join(
@@ skipping 183 matching lines @@
     Die('COMPILED var assignment not found in %s' % base.GetInPath())
   sources[base.GetInPath()] = SourceWithPaths(
       new_content,
       base.GetInPath(),
       base.GetOutPath())
 
 def LinkOrCopyFiles(sources, dest_dir):
   '''Copies a list of sources to a destination directory.'''
 
   def LinkOrCopyOneFile(src, dst):
-    if not os.path.exists(os.path.dirname(dst)):
+    try:
       os.makedirs(os.path.dirname(dst))
+    except OSError as err:
+      if err.errno != errno.EEXIST:
+        raise
     if os.path.exists(dst):
       os.unlink(dst)
     try:
       os.link(src, dst)
     except:
       shutil.copy(src, dst)
 
   for source in sources:
     LinkOrCopyOneFile(source.GetInPath(),
                       os.path.join(dest_dir, source.GetOutPath()))
@@ skipping 121 matching lines @@
     finally:
       if options.output_file:
         out_file.close()
   if options.stampfile:
     WriteStampfile(options.stampfile)
   if options.depfile:
     WriteDepfile(options.depfile, options.output_file, bundle.GetInPaths())
 
 if __name__ == '__main__':
   main()