Roll version of gsutil to 4.15.

third_party/gsutil/setup.py

 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright 2011 Google Inc. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
@@ skipping 20 matching lines @@
  * Uploading, downloading, and deleting objects.
  * Listing buckets and objects.
  * Moving, copying, and renaming objects.
  * Editing object and bucket ACLs.
 """
 
 requires = [
     'boto==2.38.0',
     'crcmod>=1.7',
     'gcs-oauth2-boto-plugin>=1.9',
-    'google-apitools==0.4.8',
+    'google-apitools==0.4.10',
     'httplib2>=0.8',
     'oauth2client>=1.4.11',
     'protorpc>=0.10.0',
     'pyOpenSSL>=0.13',
     'python-gflags>=2.0',
     'retry_decorator>=1.0.0',
-    'six>=1.8.0',
+    'six>=1.9.0',
     # Not using 1.02 because of:
     #   https://code.google.com/p/socksipy-branch/issues/detail?id=3
     'SocksiPy-branch==1.01',
 ]
 
 dependency_links = [
     # Note: this commit ID should be kept in sync with the 'third_party/boto'
     # entry in 'git submodule status'.
     # pylint: disable=line-too-long
     'https://github.com/boto/boto/archive/cb8aeec987ddcd5fecd206e38777b9a15cb0bcab.tar.gz#egg=boto-2.38.0',
@@ skipping 104 matching lines @@
             'gsutil = gslib.__main__:main',
         ],
     },
     install_requires=requires,
     dependency_links=dependency_links,
     cmdclass={
         'build_py': CustomBuildPy,
         'sdist': CustomSDist,
     }
 )