/usr/share/doc/libgl1-mesa-dri-lts-raring/changelog.Debian.gz is in libgl1-mesa-dri-lts-raring 9.1.4-0ubuntu0.1~precise2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgl1-mesa-dri-lts-raring/../libglapi-mesa-lts-raring/changelog.Debian.gz