these 2 derivations will be built:
  /nix/store/hp0ygyczn7dp2k6lzlzsj4cskmbax75b-mardi-gras-0.34.0.drv
  /nix/store/s193daagn2xlnc3wqznkrvm75kkv8d1d-check-mardi-gras.drv