/usr/share/doc/libqt4-ruby1.8/changelog.Debian.gz is in libqt4-ruby1.8 4:4.8.2-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libqt4-ruby1.8/../libqtruby4shared2/changelog.Debian.gz