these 2 derivations will be built:
  /nix/store/54ahfja9p0xpkfzgf0hm6g7fjrys0v1l-iets-0.1.0.drv
  /nix/store/y87npd0rqm2gj0gyrj8m9mai98p4nzn5-iets-langtests.drv