Title: #128: Fix group renaming issue when "id_provider = ldap" is set
hmm, perhaps we could also forcibly drop the contents of memory cache like we do with the
back end to nss back channel when the groups are renamed? Although with the renaming we
should not end up with duplicate entries anymore...
See the full comment at https://github.com/SSSD/sssd/pull/128#issuecomment-333644305