Guix QA: Branch master

Substitute availability

https://ci.guix.gnu.org/
aarch64-linux59.9%
armhf-linux23.8%
i586-gnu0.0%
i686-linux78.8%
powerpc64le-linux43.0%
riscv64-linux0.0%
x86_64-linux86.1%
https://bordeaux.guix.gnu.org
aarch64-linux96.3%
armhf-linux85.7%
i586-gnu0.0%
i686-linux89.7%
powerpc64le-linux56.8%
riscv64-linux65.6%
x86_64-linux97.9%
https://guix.tobias.gr/
x86_64-linux46.9%