these 2 derivations will be built:
  /nix/store/ndpb8561yhsjh72w1pacwnr9kx9bmafw-nixos-test-driver-pg_cron.drv
  /nix/store/fkscyi7h9f1cq6z2wbf6zzlw6h85zf8m-vm-test-run-pg_cron.drv