337102c8

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Run the internet-dependent tests purely too, via the pure-impure trick

Instead of a separate impure NixCI test job, wrap the handful of tests
that need real network access in a fixed-output derivation (the
pure-impure trick, duplicated from NorfairKing/pure-impure-nix). Nix
grants FODs network access, so these now run inside `nix flake check`
as well. The heavy offline suite stays a normal, fully reproducible
pure build.

Removes nix-ci.nix and packages.impure-test.

Suite timing

Time to Start Worker time Duration Time to finish Idle
Config 0s 7s 7s 7s 0s
Eval 7s 19s 19s 27s 0s
Build 16s 27s 1m29s 1m45s 1m18s
Suite 0s 54s 1m45s 1m45s 1m18s

Timeline

0s10s20s