This might require surfacing some other indicator in the storage engine up into replication. Also replication test infrastructure changes.
Maintain checkpoint thread timestamp information for the inMemory storage engine and thereby support recoverable rollback with inMemory
Remove the deprecated 'lastStableCheckpointTimestamp' field from replSetGetStatus response in v4.4 dev cycle
Docs for SERVER-36101: Replication should not depend on the presence of lastStableCheckpointTimestamp in status reports to identify recoverable rollback capable nodes
Don't return from ReplSetTest.initiate until there is a stable checkpoint