freebsd stable - Aug 2013 - Geom mirror regression in 9.2-RC1

I want to use old gmirror disk, created in 8.0-RELEASE on new 9.2-RC1
machine
When I attach this disk, I see only /dev/mirror/gm0, instead of
/dev/mirror/gm0 and /dev/mirror/gm0s1
I forced to manually load geom_mbr.ko to use this disk.