/usr/share/doc/libgl1-mesa-dev-lts-trusty/changelog.Debian.gz is in libgl1-mesa-dev-lts-trusty 10.1.3-0ubuntu0.2~precise2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgl1-mesa-dev-lts-trusty/../mesa-common-dev-lts-trusty/changelog.Debian.gz