Running nix on an IPv6-only host fails to instantiate nuggets and jekyll-tagging.

It's these two gems, specifically. I can build them on my local machine, and nix copy them to the server, but building them directly on the server always fails with curl: (6) Could not resolve host: rubygems.org.

(If you want to replicate it: nix build https://codeberg.org/libewa/pages/archive/main.tar.gz.)