For now pools are getting all blocks rejected by coind with this output error:
ThreadRPCServer method=submitblock
ERROR: CheckProofOfWork() : nBits below minimum work
ERROR: CheckBlock() : proof of work failed
ERROR: ProcessBlock() : CheckBlock FAILED
Devs pm me if you need anything else..
It's happened a few times already, big diff changes due to hashrate variations and timestamps in wrong order, i think..
My pool is stuck with this at the moment.