/usr/share/doc/gap-dev/changelog-4.2.Debian.gz is in gap-dev 4r7p9-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gap-dev/../gap-core/changelog-4.2.Debian.gz
/usr/share/doc/gap-dev/../gap-core/changelog-4.2.Debian.gz