[th/various-for-loopback-feature] fixes related to a feature branch

I am testing the new "loopback" feature (NetworkManager!1332 (merged)).

There are test failures, these unordered bunch of patches are to help with some of the issues I saw. I think this is generally safe.

Currently, NM's merge request 1332 is tested, so these patches are also on mr/1332 branch.