In OCaml 4.13:
Alert ocaml_deprecated_cli: Setting a warning with a sequence of lowercase or uppercase letters,
like 'CDEFLMPSUVYZX', is deprecated.
Use the equivalent signed form: +C+D+E+F+L+M+P+S+U+V+Y+Z+X+52-3.
(cherry picked from
guestfs-tools commit fa4f59e1d99c08d7e0bae2a7cb54f254a6506d67)
63c9cd933a