Ticket 47810 - memberOf plugin not properly rejecting updates
Bug Description: When the memberOf plugin tries to add memberOf attribute to
an entry during a mod-replace on a group, even though the
update to the user entry fails, but plugin still allows
the member to be added to the group.
Fix Description: During a mod/replace check and return an error if the member
update fails.
https://fedorahosted.org/389/ticket/47810
Reviewed by: nhosoi(Thanks!)
(cherry picked from commit eb54f03e240402a4bd16f9cde1d66539805f56ea)