f372039d
### opam switch create test "--formula=[\"camlp4\" \"ocaml-system\"]" --show --yes

<><> Installing new switch packages <><><><><><><><><><><><><><><><><><><><><><>
Switch invariant: ["camlp4" "ocaml-system"]
[ERROR] Could not determine which packages to install for this switch:
  * Incompatible packages:
    - (invariant) -> camlp4
    - (invariant) -> ocaml-system
    You can temporarily relax the switch invariant with `--update-invariant'


# Return code 20 #
