I thought this was a new problem... but I guess I missed this on 7.20/7.21 testing...but the confirmation of format breaks some scripts that format virtual disks:
/disk/format [find]
All data will be lost, are you sure? [y/N]:
Any chance you can add some option like force=yes/no-prompt=yes/confirm=yes/whatever to avoid the prompt to /disk/format. This comes up if you want to defconf/netinstall script that enables a /app, since it needs formatted disk...