Panic at XEN install

["matthew sporleder" <msporleder%gmail.com@localhost>]

I got the following panic while newfs's a DOMU in the install kernel
and ended up at the db> prompt.  reboot is taking a long time syncing
disks, so I'm a bit stuck.  Do I just need to update (this is
4.99.63), or am I missing something else?

Thanks,
Matt

panic: kernel diagnostic assertion "bp->b_vp == NULL || bp->b_vp->v_tag != VT_UF
S || ISSET(bp->b_flags, B_COWDONE)" failed: file "/home/msporled/netbsd/src/sys/
kern/vfs_bio.c", line 887
db> bt
breakpoint(c0426e3b,c6f7aa48,c091e100,c0328dcd,c097b400,2,c6f7aa3c,c0333ff1,c6f5
d2b8,0) at netbsd:breakpoint+0x4
panic(c0430300,c03f8b58,c0420958,c0420830,377,0,c6f7aa7c,c032912e,c03f8b58,c0420
830) at netbsd:panic+0x1b2
__kernassert(c03f8b58,c0420830,377,c0420958,c64b6000,c0bb6af8,c6f7aaac,c032930f,
c0bb6af8,0) at netbsd:__kernassert+0x39
bdwrite(c0bb6af8,0,c6f7aae8,c5d312c0,1,c0c12900,c0bb6af8,1d312c0,c5d312c0,c0c130
00) at netbsd:bdwrite+0x17e
bwrite(c0bb6af8,1,3f5,c6f7aaec,0,c5d26ebc,800,0,c6f7c044,c01008b0) at netbsd:bwr
ite+0x1cf
ffs_cgupdate(c0c12900,1,1d4,0,c0403222,c6f7c000,c5d312c0,c02f74fe,c0b8a800,c6f5d
2b8) at netbsd:ffs_cgupdate+0x1e
ffs_mount(c6f7c000,bfbfe9a4,c0b8b7e0,c6f7acd0,0,0,c6f7abdc,c6f7abe8,1f93e58,c0b8
b7e0) at netbsd:ffs_mount+0x24f
do_sys_mount(c5d312c0,0,81d3fd5,bfbfe9a4,40,bfbfeda8,0,4,c6f7ad28,0) at netbsd:d
o_sys_mount+0x6f2
sys___mount50(c5d312c0,c6f7ad00,c6f7ad28,8162310,8162000,c5d38ab8,1,81d3fd5,bfbf
e9a4,40) at netbsd:sys___mount50+0x49
syscall(c6f7ad48,1f,1f,1f,1f,bfbfe5a4,bfbfe9a4,bfbfedb8,bfbfff56,3f5) at netbsd:
syscall+0xaa