This is all I could find after co-maintaining lib for a long time.
I've had the fortune of basically not really noticing this file,
because it has had very few interactions until the confusion in
https://github.com/NixOS/nixpkgs/pull/304277
It seems to be a state of limbo, which would be nice to resolve
(with great care), but this is not urgent, and first we should
document its status.