Comment 2 for bug 122421

I can also replicate this behovior, the only way to purge ubuntu-modules is to reinstall the corresponding linux-image before removal. (or remove the postrm in /var/lib/dpkg but that's nasty).

Also, bug 138552 appears to be a duplicate of this: https://bugs.launchpad.net/ubuntu/+source/linux-ubuntu-modules-2.6.22/+bug/138552