these 2 derivations will be built:
  /nix/store/cwv5hb4jpyv952kmcwgc9p72nq06bnxm-pdfvision-0.16.0.drv
  /nix/store/0v4wvbfxi8an35qnhpsqr0yvlyjf5ajx-check-pdfvision.drv