Those are all consumed by our parser, so they all support comments.
I was considering whether they should have a license header at all,
but in the end I decided to add it because those files are often created
by copying parts of real unit files. And if the real ones have a license,
then those might as well. It's easier to add it than to make an exception.
The test is a bit messy because it must be done on a device that
enforces a tentative state for IPv6 addresses, and it appears
that the dummy device does not. So we use a bond instead.
Signed-off-by: Daniel Axtens <dja@axtens.net>