kern/126902: Kernel panic during install boot

[Jason Chambers]

There was an install of linux on the drives originally which was setup
in a LVM I believe.  It looked like FreeBSD detected this with
GEOM_LABEL messages for each partition then crashed immediately after. 
The mailing list link I included is for the most part an exact replica
of what happened.

I had the problem with both i386 and amd64 ports and did not write down
the messages.  I may have another system to try this on and will update
the PR then if it is still open.

--Jason