Ticket 49671 - Readonly replicas should not write internal ops to changelog
Bug Description: When a hub receives an update that triggers the memberOf
plugin, but that interal operation has no csn and that
causes the update to the changelog to fail and break
Fix Description: Do not write internal updates with no csns to the changelog
on read-only replicas.
Reviewed by: simon, tbordaz, and lkrispen (Thanks!!!)
(cherry picked from commit afb755bd95f1643665ea34c5a5fa2bb26bfa21b9)