these 2 derivations will be built:
  /nix/store/x3jpgndi014vjq3gp56ir4frpi2qgw96-nixos-test-driver-pg_cron.drv
  /nix/store/8k38s9qcj1pg3x2ssfbcjkxv6gvl1c3s-vm-test-run-pg_cron.drv