ENG-4347

Resolve a possible MPI deadlock with only one partition where the master dies before forwarding on the complete message and the fate of a transaction is lost.

This ran in a start cluster/kill nodes for 5 minutes/stop cluster cycle for 24 hours without a deadlock, which used to happen every 2-4 hours in the same cycle.  Jenkins is blue except for the python tests, which suck intermittently anyway.