these 2 derivations will be built:
  /nix/store/np9nrlq1vir0cgj8r2b2h98nx9vm2dgl-iets-0.2.0.drv
  /nix/store/91kj83x5k8ny33cmvwdhi2zx3bk7lhq4-iets-classic-2.34.9.drv