these 2 derivations will be built:
  /nix/store/0v9q6riv1l5bydl9wradwdqlqgkrz8pl-nixos-test-driver-postgis.drv
  /nix/store/l7sqg15nsdfkg5gz9m7k1ri979c5gm1p-vm-test-run-postgis.drv