Can't build with qcov-format as brew now pulls incompatible Ocaml

[youurayy]

$ brew install opam libev
Warning: libev 4.24 is already installed
==> Installing dependencies for opam: ocaml, ocamlbuild, camlp4, clingo, aspcud
==> Installing opam dependency: ocaml
==> Downloading https://homebrew.bintray.com/bottles/ocaml-4.06.1.high_sierra.bottle.tar.gz
...


$ opam install uri qcow-format io-page.1.6.1 conf-libev
[ERROR] io-page.1.6.1 is not available because your system doesn't comply 
with ocaml-version >= "4.00.0" & ocaml-version < "4.06.0".