these 4 derivations will be built:
  /nix/store/2f76rx5d6sf77a89jvg1lzs44mfx5rh0-nix-tarmac-0.1.0.drv
  /nix/store/jvzhmjiiy727k5xgljqifa947xgxsmmb-nix-tarmac-0.1.0.drv
  /nix/store/yw0aynippzfzxsbgb7nxql0lqrr256y7-nix-tarmac-0.1.0.drv
  /nix/store/dg7fpd720j1dgvcx94n5pkwgjhgx43h1-nix-tarmac-dispatcher.drv