these 2 derivations will be built:
  /nix/store/d8rsq9237p06bn4w9zkn5m21p3vnf1zl-nixos-test-driver-pg_cron.drv
  /nix/store/dsxmyv3k1ixrlxfjh7d28d3arpcjw6qj-vm-test-run-pg_cron.drv