[SSSD] [sssd PR#162][opened] cache_req: use own namespace for UPNs

[sumit-bose]

URL: https://github.com/SSSD/sssd/pull/162
Author: sumit-bose
 Title: #162: cache_req: use own namespace for UPNs
Action: opened

PR body:
"""
If the UPN use the same domain name as the configured domain an
unsuccessful lookup by name will already create an entry in the negative
cache. If the lookup by UPN would use the same namespace the lookup will
immediately be finished because there would already be an entry in the
negative cache.

Resolves https://fedorahosted.org/sssd/ticket/3313
"""

To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/162/head:pr162
git checkout pr162