these 2 derivations will be built:
  /nix/store/ikh7pcq8qiy4pbcpa9b15s10xryzympz-iets-0.1.0.drv
  /nix/store/s26n6zli092zraxs4m0bd19szlw70z4j-iets-langtests.drv
building '/nix/store/s26n6zli092zraxs4m0bd19szlw70z4j-iets-langtests.drv'