Handles Python3 builtin changes

Some of the builtins (like map) have changed in Python3 in a way that
can lead to broken Python2 code.

bp python3
Change-Id: I632d857bd29a23db61538755f09da68f0cf7b723

keystone/common/cache/_memcache_pool.py

@@ -27,7 +27,7 @@ import time
 
 import memcache
 from oslo_log import log
-from six.moves import queue
+from six.moves import queue, zip
 
 from keystone import exception
 from keystone.i18n import _

keystone/tests/unit/test_cache_backend_mongo.py

@@ -20,6 +20,7 @@ import uuid
 from dogpile.cache import api
 from dogpile.cache import region as dp_region
 import six
+from six.moves import range
 
 from keystone.common.cache.backends import mongo
 from keystone import exception