/usr/share/doc/libgnomemm-2.6-dev/changelog.Debian.gz is in libgnomemm-2.6-dev 2.30.0-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgnomemm-2.6-dev/../libgnomemm-2.6-1c2/changelog.Debian.gz