these 2 derivations will be built:
  /nix/store/mqfbns7fhvwgp2vqnafx66s9gy3gjwgc-iets-0.1.0.drv
  /nix/store/c9snb9r54zfq1z2mwdmlaifzh5alk3v8-iets-langtests.drv