these 2 derivations will be built:
  /nix/store/gmbvp5bm63p69gc3ip6fdj7fb3gj96ls-unreal-agent-0.3.1.drv
  /nix/store/gy5ir8r61rja4zvkv9k5my2ymy4vf5lv-check-unreal-agent.drv