ELPA automation scripts generate a duplicate of shell-command-plus

[AndersonTorres]

When update-elpa script is executed inside pkgs/applications/editors/emacs/elisp-packages/ of Nixpkgs repo, it always duplicate the specific recipe shell-command-plus.

Certainly it can be fixed by hand, but it is always a tedious procedure.

Here is the latest time the bug was reported at Nixpkgs:

https://github.com/NixOS/nixpkgs/issues/119586

[AndersonTorres]

https://github.com/nix-community/emacs2nix/issues/54