Info
When reading after a cluster time at level local, it is possible to have outstanding uncommitted transactions hide data assigned to an earlier cluster time. This is because optimes are not assigned by commit order.
To fix this, we will need to block readAfterClusterTime reads until all transactions prior to the specified cluster time have committed.
Note that it will be still be possible to return data before transactions after the specified cluster time have committed; this will be okay.
