these 2 derivations will be built:
  /nix/store/l5j2kik16b9ff60qdh3w0bydf3dqlr7n-iets-0.1.0.drv
  /nix/store/h1q3jd6n6wws3c98wy39big2qy4g7j86-iets-langtests.drv