these 2 derivations will be built:
  /nix/store/1y77d4ykwxqpkfm7kppdssx1v953m9g8-nixos-test-driver-postgis.drv
  /nix/store/i7nr44q3cglba0gfxd2ycdp38qdq3fhr-vm-test-run-postgis.drv