bug#63230: ‘guix shell’ cache is system-independent

[Ludovic Courtès]

I just noticed that the ‘guix shell’ cache doesn’t take the system type
into account, which is problematic:

--8<---------------cut here---------------start------------->8---
$ guix shell -s aarch64-linux guile guile-fibers -- guile  -q
GNU Guile 3.0.9
Copyright (C) 1995-2023 Free Software Foundation, Inc.

Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
This program is free software, and you are welcome to redistribute it
under certain conditions; type `,show c' for details.

Enter `,help' for help.
scheme@(guile-user)> %host-type
$1 = "i686-unknown-linux-gnu"
scheme@(guile-user)> ,q
$ guix shell -s powerpc64le-linux guile guile-fibers -- guile  -qGNU Guile 3.0.9
Copyright (C) 1995-2023 Free Software Foundation, Inc.

Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
This program is free software, and you are welcome to redistribute it
under certain conditions; type `,show c' for details.

Enter `,help' for help.
scheme@(guile-user)> %host-type
$1 = "i686-unknown-linux-gnu"
scheme@(guile-user)> ,q
$ guix describe
Generation 259  May 01 2023 23:40:54    (current)
  guix 39ba8a1
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 39ba8a10971f15264966823e8696d63c2995df86
  shepherd 6a2b366
    repository URL: https://git.savannah.gnu.org/git/shepherd.git
    branch: master
    commit: 6a2b36635d1588a07660403e137134fddf5b4923
--8<---------------cut here---------------end--------------->8---

One can work around it by passing ‘--rebuild-cache’.

Ludo’.