Hello! I maintain modus-themes[1] for Emacs team. In the process of upgrading to upstream version, I have come across license-problem-gfdl-invariants[2] in ~doc/modus-themes.info~ [3].
I do not understand legality of the matter fully and seek advice as to how this can be easily handled. I am also including Protesilaos (upstream) to have a conversation with everyone included. I think it will be of great help if debian-legal could explain the case and possible solutions to Emacs team as well as upstream. Thanks! [1]: https://salsa.debian.org/emacsen-team/modus-themes [2]: https://wiki.debian.org/qa.debian.org/gfdlinvariant