zpool upgrade, can't boot

[Jeff Blank]

Hi,

I recently upgraded from 8.0-STABLE to 8.2-STABLE (Apr. 29 checkout)
and upgraded my zpool (includes root FS) from v13 to v15.  This is a
dual-boot laptop, so I'm using MBR/boot0 and not GPT.  Here's what
happens when I boot:

F1  Win
F2  ?
F3  FreeBSD

F6 PXE
Boot:  F3
ZFS: unsupported ZFS version 15 (should be 13)
No ZFS pools located, can't boot

I've googled around, but I can't find anything relevant for MBR/boot0
configurations, just GPT.  I've ensured that the loaders and
boot0/boot1/boot2 are all new, and I rebuilt/reinstalled them in a
fixit environment just to be sure.  I also ran 'boot0cfg -B' (with an
appropriate -b), but nothing has changed.  How can I get my pool
booting again?

thanks,
Jeff