these 2 derivations will be built:
  /nix/store/6gbyzna1i7vy88kq5jl6nxbmjck2nk2j-hol-guard-3.19.0.drv
  /nix/store/dpvz12n44b1j95xl0g7nq6mmx3hlnh71-check-hol-guard.drv