/usr/share/doc/libpgocaml-ocaml-dev/changelog.Debian.gz is in libpgocaml-ocaml-dev 2.2-1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libpgocaml-ocaml-dev/../libpgocaml-ocaml/changelog.Debian.gz