"Michael Renzmann" [off-list ref] writes:

One thing that probably should be added is an explanation of the
"Changes-licensed-under:" tag that is used in some patches.

I'm not sure it's that easy.

If a patch doesn't create a derivative work (can't be copyrighted)
the licence doesn't matter/exist.

If a patch creates a derivative work then the author can distribute
under a different licence, but the new licence must be written into
the source file being patched anyway.
-- 
Krzysztof Halasa