these 2 derivations will be built:
  /nix/store/6b7mf4z57z3fkhx56bj63njxlkb9w341-pdfvision-0.16.0.drv
  /nix/store/4j3ydqdq6hx65q1ad9c1lqmlqafzs8i3-check-pdfvision.drv