Relay submitted a descriptor with 0 DirPort due to a self-test race condition
A relay operator reports their relay submitted a descriptor with a 0 DirPort after a version upgrade, then 62 seconds later submitted a descriptor with the configured DirPort.
Unfortunately, this was right on the consensus deadline, so they had one consensus where their DirPort was 0.
https://lists.torproject.org/pipermail/tor-relays/2016-January/008523.html