When making a node with existing data to rejoin a replset with initial sync, triggering an oplog replay can crash the sync because writing down the top of the oplog entry which was already replicated to the sync node can have a conflicting timestamp with the stable timestamp. 

This is however an edge case and should not be done by the users. A crash is expected in this case. As a result, we would just want to fix the test. We can potentially prevent the sync source from writing down extra oplog entries during the initial sync.