/usr/share/doc/python-setproctitle-dbg/changelog.Debian.gz is in python-setproctitle-dbg 1.0.1-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/python-setproctitle-dbg/../python-setproctitle/changelog.Debian.gz