these 4 derivations will be built:
  /nix/store/11ghcydia8mmaxp1gky46apvyrkl9333-nix-tarmac-0.1.0.drv
  /nix/store/hy3d4q5wixr2iw2kvk45b9lzrzvjmm4d-nix-tarmac-0.1.0.drv
  /nix/store/md15ljhcwhy090kygryf7mkblvz5gf2z-nix-tarmac-0.1.0.drv
  /nix/store/gis2wlm49mgv1p5ag6gkn61gi3nc36d4-nix-tarmac-dispatcher.drv