We don't serve substitutes of texlive-texmf. We achieve this by configuring nginx to return "410 Gone" [0].
This requires users to build it with '--fallback', and the Guix error message even recommends this, but many users ask about it on IRC. I think we should mark it '#:substitutable? #f' so that, IIUC, Guix will download and build texlive-texmf from the upstream source automatically, without stopping or requiring users to use '--fallback'. If everyone agrees to this, exactly which package or packages should be have this option set? There are several related variables in (gnu packages tex) and I'm not sure how to achieve the desired goal of making this "just work" for our users. [0] http://git.savannah.gnu.org/cgit/guix/maintenance.git/tree/hydra/nginx/hydra.gnu.org-locations.conf#n14
