these 4 derivations will be built:
  /nix/store/rh353imlr7j1phy6ld8631gcw2znbj14-herdr-core-0.1.21-vendor.drv
  /nix/store/cfr1fd5kxkd2q1pp0xwdy1qi9n9miz8b-herdr-core-0.1.21.drv
  /nix/store/mp3dahvi415gy10y4w46wbikzv1bxbxz-herdr-app-0.1.15.drv
  /nix/store/rxgpxr7pzh5w2g5jk5cy4cnqc2hidkig-check-herdr-app.drv