/usr/share/doc/libgeos-ruby1.8/changelog.Debian.gz is in libgeos-ruby1.8 3.4.2-4ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgeos-ruby1.8/../ruby-geos/changelog.Debian.gz
/usr/share/doc/libgeos-ruby1.8/../ruby-geos/changelog.Debian.gz