these 2 derivations will be built:
  /nix/store/ygrd9pv817jrqrg32dqxnrlzdn5hk0l5-iets-0.1.0.drv
  /nix/store/2n0xdy6x2m22a1vlyjhl6p6qkyvhpv9q-iets-langtests.drv