/usr/share/doc/libgl1/changelog.Debian.gz is in libgl1 1.0.0-2ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgl1/../libglvnd0/changelog.Debian.gz
/usr/share/doc/libgl1/../libglvnd0/changelog.Debian.gz