I just downloaded it today (Jan 19 2006).
Anyway the bug is ... when it is copying across hacks, it will copy across /var/hack. Unfortunately the slicer has not mounted the new /var at /install/var, so as a result the /var/hack is copied into the new / instead of the new /var. In my case this filled up the /.
It gets worse ... on a tivo reboot, the new /var is mounted and effectively hides the copy of /var/hack on the newly created system. This means you cannot do anything such as move /var/hack back onto /var. I eventually had to create this script: /init/003_varh.init to fix it:
mount -n -o remount,rw /
umount -n /var
mv -f /var/hack /h
mount -n /var -n
mount -n -o remount,ro /
a reboot later and my directory was now available at /h and I was able to delete it.
The slicer should mount the new /var to be at /install/var so it copies /var directories to the right place.
I hope this bug report helps. ps. Tivo is working at 6.3 though. Good job!