/usr/share/doc/libcos4-1-dbg/changelog.Debian.gz is in libcos4-1-dbg 4.1.6-2ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libcos4-1-dbg/../libomniorb4-1/changelog.Debian.gz
/usr/share/doc/libcos4-1-dbg/../libomniorb4-1/changelog.Debian.gz