Remove replication event from pending when runway is allowed

Consider a replication event not pending anymore *only if* the runway
is free and allowed to run. Removing it too early would result in a
ghost event which isn't officially pending but that will be eventually
run when rescheduled.

Change-Id: Ib0ffa3bec7a6d5d5be56e78a677e8b2133f91e18