dfly-2.0.0-REL: panic: hammer: insufficient undo FIFO space!

[M.K.]

OS: dfly-2.0.0-REL

I backed up my 5GB win2k ntfs partition to a disk image file on my Hammer FS
(6GB in size). When removing the image file, panic occurs.
To reproduce panic:

NOTE: assuming Hammer FS is mounted on /hammer dir and /root is symlinked to
/hammer/root.
# cd /root
# cat /dev/ad0s1 > c.img
# rm c.img
  PANIC
Screen Shot of Panic: http://www.bmk.com.au/webshare/hammer_panic.jpg

My dmesg: http://www.bmk.com.au/webshare/dmesg.txt

My fdisk, disklabel & fstab: http://www.bmk.com.au/webshare/labels.txt