#440 ABIv0: Lock-up mounting a disk image

[Neil Cafferkey]

Mounting a disk image using the same handler as the system volume uses causes a lock-up. This seem to be because the device-based handler system can't access the system volume to open fdsk.device while the same handler is mounting the image.

Example: Boot from "CD2:" and then run "Mount CD0:".

This only affects ABIv0 and is probably not worth fixing.