these 2 derivations will be built:
  /nix/store/pwgh4sqf5q1xyz5p81hw2lyhfwciizz5-nixos-test-driver-pg_cron.drv
  /nix/store/rj198a1zv64vk49pbdjflbhk4wbhnn2b-vm-test-run-pg_cron.drv