these 4 derivations will be built:
  /nix/store/dsap7p0nbxnbmqhflki366wa8scwigkj-nix-tarmac-0.1.0.drv
  /nix/store/dx6bm9pmk3hmrjw585m898x5hhlqsyd5-nix-tarmac-0.1.0.drv
  /nix/store/ldk31psr6d1gc6r6d71mn6zhwcjvk718-nix-tarmac-0.1.0.drv
  /nix/store/08936kkfaxbx0l9x9jp9346v1sxk8gfv-nix-tarmac-dispatcher.drv