these 3 derivations will be built:
  /nix/store/7xpbgvl1kd7si8kn5hb78n5ya3k15jxk-source.drv
  /nix/store/9i50dyblnb5bjbkij6a08lwii7ckh766-herdr-eternal-deps-0.1.0.drv
  /nix/store/4hpdi8d3jjy30k87njmywgqi2d1hdxml-herdr-eternal-test-0.1.0.drv