/usr/share/doc/gnuplot-x11/changelog.Debian.gz is in gnuplot-x11 4.4.3-0ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gnuplot-x11/../gnuplot-nox/changelog.Debian.gz
/usr/share/doc/gnuplot-x11/../gnuplot-nox/changelog.Debian.gz