Villemoes

Actually, there's no need for an extra_sha256, only an extra_files (or whatever name is appropriate) that would also be included in the existing sha256. And looking closer, it actually seems...

So I went ahead and tried to refactor the checksumming code to make it easy to hook up some "also checksum these files", see #348 .

> This is sysv compat code. We do not extend on it, as that syntax is defined and "owned" by sysvinit. We are happy to catch up with sysvinit here,...

> I'm okay with the concept and the interface, but I don't like piping through cat. Why not? It's not performance critical, and even so, I don't think it will...