Docserver: Fix GitHub authentication issues that have recently cropped up: use

chrome/common/extensions/docs/server2/appengine_url_fetcher.py

 # 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.
 
 import base64
 import posixpath
 
-from appengine_wrappers import urlfetch
+from appengine_wrappers import GetAppVersion, urlfetch
 from future import Future
 
 
 class _AsyncFetchDelegate(object):
   def __init__(self, rpc):
     self._rpc = rpc
 
   def Get(self):
     return self._rpc.get_result()
 
 
 def _MakeHeaders(username, password):
-  headers = { 'Cache-Control': 'max-age=0' }
+  headers = {
+    'User-Agent': 'Chromium docserver %s' % GetAppVersion(),
+    'Cache-Control': 'max-age=0',
+  }
   if username is not None and password is not None:
-    headers['Authorization'] = 'Basic %s' % base64.encodestring(
+    headers['Authorization'] = 'Basic %s' % base64.b64encode(
         '%s:%s' % (username, password))
   return headers
 
 
 class AppEngineUrlFetcher(object):
   """A wrapper around the App Engine urlfetch module that allows for easy
   async fetches.
   """
   def __init__(self, base_path=None):
     assert base_path is None or not base_path.endswith('/')
@@ skipping 11 matching lines @@
     rpc = urlfetch.create_rpc()
     urlfetch.make_fetch_call(rpc,
                              self._FromBasePath(url),
                              headers=_MakeHeaders(username, password))
     return Future(delegate=_AsyncFetchDelegate(rpc))
 
   def _FromBasePath(self, url):
     if self._base_path is not None:
       url = posixpath.join(self._base_path, url) if url else self._base_path
     return url