Title: #128: Fix group renaming issue when "id_provider = ldap" is set
There was a recent confusion about this PR. I thought that this should actually have been
marked as changes requested to solve @lslebodn 's comment from Oct 2 that mentioned
expiring the entries from the memory cache. Other than that, this PR looks OK to me and
there is even a test in a different PR.
See the full comment at https://github.com/SSSD/sssd/pull/128#issuecomment-364146093