these 2 derivations will be built:
  /nix/store/p50x2zpl4jp1fpamdg2pldjg3n7k2mcl-nixos-test-driver-pgtap.drv
  /nix/store/04p2f6m3da026i0j3yfyx8z0fcgf5gj6-vm-test-run-pgtap.drv