these 2 derivations will be built:
  /nix/store/gpvh7awhb7cmk4a60zxn48lcizs6g6g4-unreal-agent-0.3.1.drv
  /nix/store/iwbq87c0yn1nc6zlp6dp8nnxrvlwwzf3-check-unreal-agent.drv