/usr/share/doc/lxsession-dbg/changelog.Debian.gz is in lxsession-dbg 0.4.9.2+git20140410-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/lxsession-dbg/../lxsession-logout/changelog.Debian.gz