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.
For netdev, config files are loaded twice, and the first time,
only Match and NetDev setions are read. So, the test given by
the previous commit covers only the second loading.
This adds another test that also covers the first loading.
Zbigniew Jędrzejewski-Szmek
Yu Watanabe