these 2 derivations will be built:
  /nix/store/k1gm1ggvs2dpv07l42mx4v8839yhvv4m-nixos-test-driver-pg_cron.drv
  /nix/store/rdxk5gz0f7xfv4c0jxn67xilf0g1g2y2-vm-test-run-pg_cron.drv