Bug#867590: networkd removes statically set default route when RA expires

[jkhsjdhjs]

Hello,

I experienced the same or a very similar bug nearly two years ago on a 
gentoo server. I reported it to systemd upstream, it is tracked here: 
https://github.com/systemd/systemd/issues/7354

Today, yuwata created a pull request which attempts to fix the problem: 
https://github.com/systemd/systemd/pull/12971

Unfortunately I don't have said gentoo server anymore, thus I can't test 
the PR either.

Best Regards,

Leon