▲  mat@localhost ~  $ guix pull --substitute-urls=https://bordeaux.guix.gnu.org
Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
Updating channel 'nonguix' from Git repository at 'https://gitlab.com/nonguix/nonguix'...
Updating channel 'private' from Git repository at 'file:///home/mat/.config/guix-private-channel'...
Updating channel 'pkill9-channel' from Git repository at 'file:///home/mat/.config/guix-pkill9-channel'...
Building from these channels:
  pkill9-channelfile:///home/mat/.config/guix-pkill9-channel	cc7c5df
  private   file:///home/mat/.config/guix-private-channel	1c92869
  nonguix   https://gitlab.com/nonguix/nonguix	ec7c7b8
  guix      https://git.savannah.gnu.org/git/guix.git	d1c6b8d
Computing Guix derivation for 'x86_64-linux'... |
The following derivation will be built:
   /gnu/store/mmhihr7y7i17x7zgz6pfw1ckff84dzzd-profile.drv

building package cache...
/builder for `/gnu/store/2qbc72gzy15dhs97lib1n38a1j6c6ri0-guix-package-cache.drv' failed to produce output path `/gnu/store/7lhi2w7anfgmzx597gx3x5hv4dnhkbhi-guix-package-cache'
build of /gnu/store/2qbc72gzy15dhs97lib1n38a1j6c6ri0-guix-package-cache.drv failed
View build log at '/var/log/guix/drvs/2q/bc72gzy15dhs97lib1n38a1j6c6ri0-guix-package-cache.drv.bz2'.
cannot build derivation `/gnu/store/mmhihr7y7i17x7zgz6pfw1ckff84dzzd-profile.drv': 1 dependencies couldn't be built
guix pull: error: build of `/gnu/store/mmhihr7y7i17x7zgz6pfw1ckff84dzzd-profile.drv' failed