[nsd-users] fix patch multi-master-check

[manabu-s at iij.ad.jp]

Hi

Fix for expire state can't transition to ok,
when masters includes broken master.

https://gist.github.com/mimuret/5924683e2719769fa55e540fbbf14634

-- 
Manabu Sonoda <manabu-s at iij.ad.jp>
Internet Initiative Japan Inc.