Comment 2 for bug 1605052

The issue is that snap-confine has a debian/snap-confine.maintscript that deal with upgrades in the debian version of the package. However we do not have a version of snap-confine in xenial yet.

Fwiw, this is a bug in dpkg-maintscript-helper because it should deal with the case that there is no previous version without showing a huge error message: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=582819

We have two options here, backport the fix for dpkg-maintscript-helper or trying to workaround this issue in snap-confine.