HEAD memsticks broken?

Hi,

I suspect something is broken with memsticks built from HEAD. I noticed that I
couldn't boot the latest HEAD (amd64) memstick snapshot on two machines
(Lenovo X220 and HP ProLiant ML350 G5). Trying snapshots from the FreeBSD.org
FTP or allbsd.org makes no difference.

It boots fine until mountroot, where I get (help messages removed):

Trying to mount root from ufs:/dev/ufs/FreeBSD_Install [ro,noatime]...
mountroot: waiting for device /dev/ufs/FreeBSD_Install ...
Mounting from ufs:/dev/ufs/FreeBSD_Install failed with error 19.
Loader variables:
 vfs.root.mountfrom=ufs:/dev/ufs/FreeBSD_Install
 vfs.root.mountfrom.option=ro,noatime
mountroot>

I then tried a few older HEAD snapshots, but the problem persists. I've tried
the following HEAD snapshots available at allbsd.org:

FreeBSD-10.0-HEAD-r246472-JPSNAP-amd64-amd64-memstick.img
FreeBSD-10.0-HEAD-r243701-JPSNAP-amd64-amd64-memstick.img
FreeBSD-10.0-HEAD-r242396-JPSNAP-amd64-amd64-memstick.img
FreeBSD-10.0-HEAD-r241545-JPSNAP-amd64-amd64-memstick.img
FreeBSD-10.0-HEAD-r241070-JPSNAP-amd64-amd64-memstick.img

I've also tried the following two snapshots from FreeBSD.org:

FreeBSD-10.0-CURRENT-amd64-20130202-r246254-memstick
FreeBSD-10.0-CURRENT-amd64-20130108-r245175-memstick

None of the above works on these machines. Problem is exactly the same.

Next up, I tried a 9.1-RELEASE amd64 memstick from FreeBSD.org. Boots without
any problems whatsoever. After that, tried the latest (r246455) RELENG_9 amd64
snapshot from allbsd.org - also boots fine on both machines.

Any ideas?

-- 
Joel