This should be a safe assumption, but hughsaunders ran into a deployment
where a small subset of users (backed by AD) were configured with:
[ldap]
user_name_attribute = sAMAccountName
Where sAMAccountName happens to be an optional attribute in some LDAP
systems, resulting in those users not having "name" attributes available
via Keystone's API.
closes-bug: 1431942
Change-Id: Ic69e571c71fd462c65791800eaaa474917dec2ef
903e7b3d0d