these 2 derivations will be built:
  /nix/store/grznic2vid1d2hxwrqak4x3m69xh0wbq-hol-guard-3.19.0.drv
  /nix/store/m6kx43krzi0h4lxn8jxkk2j2l3zn1dpb-check-hol-guard.drv