Code review comment for ~danilogondolfo/network-manager/+git/network-manager:new_autopkgtests

Thank you very much, Danilo! LGTM.

praise: I really like how you enhanced the generic NetworkManager tests in nm.py along the way and resolved an old FIXME!

I left two little (non-blocking) comments inline.

I moved the MP state to "Work in progress" as it's still pending the corresponding update to libnetplan. IMO this can be merged as soon as the new Netplan version hits mantic-proposed! This is the point where the new tests should start passing.