/usr/share/doc/linux-tools-4.4.0-78-generic/changelog.Debian.gz is in linux-tools-4.4.0-78-generic 4.4.0-78.99.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/linux-tools-4.4.0-78-generic/../linux-tools-4.4.0-78/changelog.Debian.gz