core: Unable to search on domain for users with some search options.

Search failed, when try to search user on domain
with special keyword.

This happens when user search by lastname, department
and title.

Change-Id: I59396ef6f549b06ccd0bf492c6857db228a23592
Bug-Url: https://bugzilla.redhat.com/975380
Signed-off-by: Ravi Nori <rnori@redhat.com>