I'd strongly recommend revising your "mandatory" policy. Running such an old release is an exceptionally bad idea, replication aside.
I've just upgraded OpenLDAP to the 2.4.57 version. For now it's the closer I can get to the most recent release. I don't know if the 2.4.57 version can safely do replication. Anyway I can live without replication for a while, so I'll let it disabled.