wedges, why is dk0 root?

[Stephen Borrill <netbsd%precedence.co.uk@localhost>]

I added a 2nd (virtual) HDD to my installed VM, created a GPT and then a 
ufs wedge on it. At a reboot, it now decides that the wedge is the root 
device:
dk0 at xbd1: 8f7dbfb4-0f7f-11e5-895b-5acb6b8c1887
dk0: 20971453 blocks at 34, type: ffs
boot device: dk0
root on dk0
root file system type: ffs
warning: no /dev/console
exec /sbin/init: error 2

NetBSD builder7 7.0_BETA NetBSD 7.0_BETA (XEN3_DOMU.201506020220Z) amd64

Is this right? It didn't happen with netbsd-5.

--
Stephen