Comment 12 for bug 628418

Beware that Dustin's testing approach will not work in this case, because the grub-installer patch adds a new template and udpkg -i needs to be in the right context to talk to the running debconf frontend. Furthermore, it's very important to use udpkg --unpack here since otherwise udpkg will run the new postinst on the spot.

This is awkward - you need to insert the udpkg --unpack call into some carefully chosen postinst that's already sourced the debconf confmodule. Don't worry about it in this case, as I'll sort it out.