Rerunning commitTransaction, with the recoveryToken added in
SERVER-37344, on a new mongos blocks forever. It also seems to get the cluster into a state where it cannot accept any writes (even to other databases) but the shard still reports itself as the primary. Also, both the shard server and config server do not shutdown normally and need to be killed with SIGKILL.
To reproduce start a sharded cluster with at least two mongoses (my cluster a one config server and a one node shard). Run the repro script: reproHangingCommit.js
db.currentOp() reports an ongoing coordinateCommitTransaction command that never ends. I've attached an example currentOp output at the bottom of the repro script.