Comment 51 for bug 1913421

I have implemented the SRU now as discussed.

Retest LGTM
1. install (no files, no mount)
2. upgrade/reinstall (modules saved, mount)
3. upgrade/reinstall (modules saved, mount - no double mount or errors)
4. moving files away still late loadable
5. on remove current modules stay behind, the rest stays
6. on purge all is gone

Behavior wise this was mostly ok already, here the items I found:

My tests identified a weakness that actually would have happened before as well but was somewhat masked. That is if a guest is running that uses the fallback mechanism we have:
  umount: /run/qemu: target is busy.
  rm: cannot remove '/run/qemu': Device or resource busy
I think in those cases we just want it to stay silent, on a reboot it will be gone and we do NOT want to kill the guests that stay up.

Furthermore Bionic has not yet --quiet
  umount: unrecognized option '--quiet'
Easy to drop

And there is one imperfection left which is the test on the noexec reporting this on upgrade.
  /var/lib/dpkg/info/qemu-block-extra:amd64.prerm: 29: /var/run/qemu/exec: Permission denied
I think that is just a matter of output redirection and will add that.
But it postpones the refresh of the MR by another rebuild cycle.

New builds uploaded to the PPA.