/usr/share/doc/libpolkit-agent-1-0/changelog.Debian.gz is in libpolkit-agent-1-0 0.104-1ubuntu1.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libpolkit-agent-1-0/../libpolkit-gobject-1-0/changelog.Debian.gz