Having discussed it today, the problem seems to relate to the use of Guile 2.0.5: the web client would not work as expected, and thus the substituter would erroneously think that the queried store paths are missing on hydra.gnu.org, and cache that.
I believe that commit 1c9e7d6 partly solves that. That is, if you ‘rm -rf /nix/var/nix/substitute-binary/’, and then run ‘guix build hello -n’, it should report things that it would download. However, if you type ‘guix build hello’, it will barf in ‘filtered-port’ when trying to actually download the thing. If you run Guile 2.0.5, can you confirm that my predictions are correct? :-) (Again, there’s no problem with Guile > 2.0.5.) Ludo’.
