Comment 23 for bug 1847361

I see a drawback, people could want to "apt remove" a package to stop its functionality.
And with the fix for this bug this will only be true after a reboot.

The conceptual way out of this as much as possible IMHO is to:
- trigger doing the backup to /var/run only on upgrade but not on remove
- have "purge" and "remove" delete the /var/run/qemu/#files# completely
  - we can't remove the dir as we could have e.g. gui and block packages handled differently

This isn't perfect there could be special-cases constructed to make this not work.
But again - it won't break just not get the benefit of "working on upgrade" and OTOH we want to keep the promise that "remove/purge" will make things stop to work/exist.

Note: "deconfigure" in this case matches "upgrade"