these 2 derivations will be built:
  /nix/store/2f10g0zjm0ydd0w21g6g3wfnd8c5bp0n-iets-0.1.0.drv
  /nix/store/6m395nig6inirqzj56a9n1q4bwfpgc2k-iets-partest.drv