[bug#68163] [PATCH] gnu: Prevent stale cache use when `%package-module-path' is parameterized.

[antlers]

Some final thoughts I had I as I was moving-on:

1.) Mailing list guidelines prob say not to link to Gists, I made sure to 
include all relevant content in-line and wouldn't have attached them on their 
own anyways. They're there for the adventurous.

2) No, I don't want to put my packages in a separate channel-- I believe that 
the average Guix user has one channel for both their configuration and custom 
packages / services (I don't mean this in a demanding way, clearly happy to 
scratch my own itches, just anticipating the suggestion).

3.) Yes, my `extract-emacs-packages' parser really does support command-line 
transformation options and comments in use-package `:guix` blocks-- that 
snippet is verbatim.

4.) cc davie, he might get a kick outta that snippet

5.) I started preparing the reduced example as a `guix repl' session until I 
realized it has to be a real file for `module-filename' and `fold-packages' to 
work-- it could expose a module search-path, but I don't *think* there's a real 
use-case for that :p