Code review comment for ~utkarsh/ubuntu/+source/multipath-tools:merge-multipath-tools-impish

Few things for Robie while reviewing:

-> Because of the whole dropping the undocumented patch situation, I've added an empty commit so that it stays in the git history as well (besides the d/ch entry, of course).

-> Since this required splitting of commits (about 25ish), I hope I did not mess up somewhere; apologies if I did! :D

-> Although independent, the PR associated w/ what we discovered in the handbook is here: https://github.com/canonical/ubuntu-maintainers-handbook/pull/14.

Let me know if there's anything that's needed from my end or if I can help make your reviewing easier. TIA! \o/