Comment 3 for bug 69470

So, regardless of the cause, dpkg crashed and ubiquity fell over in a heap. Obviously it would be better if dpkg didn't crash, but what you really want if possible is for the installation to limp along and complete as best it can so that you can (a) use your system and (b) investigate in a more congenial environment.

I'm going to attempt to detect this condition, display a warning message, and continue; this also fixes a couple of other sets of bugs.