/usr/share/doc/libopus-ocaml-dev/changelog.Debian.gz is in libopus-ocaml-dev 0.1.0-4build4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libopus-ocaml-dev/../libopus-ocaml/changelog.Debian.gz