After upgrade from 9-STABLE to 10-STABLE "shutdown -h now" doesn't halt, but reboot system.

Sat Apr 12 13:05:32 UTC 2014

Hello, FreeBSD.

 It breaks UPS usage completely -- system reboots instead of waiting for
power off if it is "halted" by UPS monitoring (nut).

 System is Q35-based MoBo with E8400 CPU, nothing fancy or special.

 How could I debug this problem to provide more information?

-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>