[gentoo-licenses] The GPL-2, modified works, and ChangeLog files

[Ulrich Mueller]

The GPL-2 says in clause 2.a) about distribution of modified versions:

    a) You must cause the modified files to carry prominent notices
    stating that you changed the files and the date of any change.

Now current plans for the transition to git include dropping of
ChangeLog files from the tree distributed to users via rsync (and
presumably also from snapshot tarballs). The question is if the GPL-2
allows us to do that, or if we have to add ChangeLog files generated
from the git log.

The GPL's model seems to assume the simple situation that there is
a single author (= copyright holder) who distributes an "original
version" of a program, and then another person who modifies it and
distributes that "modified version" under clause 2).

How does this translate to our situation with many developers
committing to a central repository? Is the latest version of the tree
the "original work", with a collective copyright of all contributors?
Or is each commit a "modified version" of the previous? I believe that
in the first case (distribution of the original work) modification
notices wouldn't be needed at all, but that in the second case the GPL
would require them.

Ulrich