[Nut-upsuser] [bug] Unexpected shutdown

[unreal]

Hello,

I had a brief power fluctuation earlier, which caused the UPS to power up
a few seconds. Then suddenly NUT was busy shutting down my server, after
full power had already been restored.

Here's the logs:

Jun  6 13:28:30 hell upsmon[607]: UPS apc620 at localhost on battery
Jun  6 13:28:35 hell apcsmart[602]: Communications with UPS lost - check
cabling
Jun  6 13:28:35 hell upsd[604]: Data for UPS [apc620] is stale - check driver
Jun  6 13:28:35 hell upsmon[607]: Poll UPS [apc620 at localhost] failed -
Data stale
Jun  6 13:28:35 hell upsmon[607]: Communications with UPS
apc620 at localhost lost
Jun  6 13:28:40 hell upsmon[607]: Poll UPS [apc620 at localhost] failed -
Data stale
Jun  6 13:28:45 hell upsmon[607]: Poll UPS [apc620 at localhost] failed -
Data stale
Jun  6 13:28:50 hell upsmon[607]: Poll UPS [apc620 at localhost] failed -
Data stale
Jun  6 13:28:50 hell upsmon[607]: Executing automatic power-fail shutdown
Jun  6 13:28:50 hell upsmon[607]: Auto logout and shutdown proceeding

So it appears upsd lost communication with the UPS, but the real problem
was that after the 15 sec MAXAGE period, upsmon decided it was necessary
to shutdown.

Why? Any ideas?