/usr/share/doc/linux-tools-4.2.0-19-generic/changelog.Debian.gz is in linux-tools-4.2.0-19-generic 4.2.0-19.23~14.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/linux-tools-4.2.0-19-generic/../linux-lts-wily-tools-4.2.0-19/changelog.Debian.gz