When we add/remove reverse members it looks like we're operating on group A
but we're really operating on group B. This adds/removes the member attribute
on group B and the memberof plugin adds the memberof attribute into group A.
We need to give the memberof plugin a chance to do its work so loop a few
times, reading the entry to see if the number of memberof is more or less
what we expect. Bail out if it is taking too long.
ticket 560