'Fetches authentication cookies for an authentication token.
Args:
auth_token: The authentication token returned by ClientLogin.
Raises:
HTTPError: If there was an error fetching the authentication cookies.'

def _GetAuthCookie(self, auth_token):

    continue_location = 'http://localhost/'
    args = {'continue': continue_location, 'auth': auth_token}
    login_path = os.environ.get('APPCFG_LOGIN_PATH', '/_ah')
    req = self._CreateRequest(('%s://%s%s/login?%s' % (self.scheme, self.host, login_path, urllib.urlencode(args))))
    try:
        response = self.opener.open(req)
    except urllib2.HTTPError as e:
        response = e
    if ((response.code != 302) or (response.info()['location'] != continue_location)):
        raise urllib2.HTTPError(req.get_full_url(), response.code, response.msg, response.headers, response.fp)
    self.authenticated = True
