d) regarding saving the preferences backup in etc/apt/preferences.d.save, and the "risk" of not cleaning up and leaving this directory there, why not use a temporary directory, or even preferences.d.save in /tmp? Not a blocker, but I was reading your regression potential analysis, and wondered. Maybe it doesn't fit well with how all these scripts work together?
d) regarding saving the preferences backup in etc/apt/ preferences. d.save, and the "risk" of not cleaning up and leaving this directory there, why not use a temporary directory, or even preferences.d.save in /tmp? Not a blocker, but I was reading your regression potential analysis, and wondered. Maybe it doesn't fit well with how all these scripts work together?