bug#46849: ELPA packages are fetched from unstable url -> not reproducible

[Johannes Rosenberger]

Hey Guixers,

i think guix makes the same mistake Nixpkgs make (at least when I looked up 
what guix is doing around two weeks ago):

They fetch the uncompressed tars built by ELPA.

These are only available for the newest version of a package.
ELPA keeps compressed archives only of around 20 hand-selected versions. 
All package versions are kept in their git repo, which is a complete archive,
but there you must somehow extract the commit hash of a version.

Details are here:

- https://github.com/ttuegel/emacs2nix/issues/55
- https://github.com/NixOS/nixpkgs/issues/110796
- https://debbugs.gnu.org/cgi/bugreport.cgi?bug=46441

I proposed possible solutions in the Nixpkgs issue.


Best,

Johannes