/usr/share/doc/libfastjet-dev/changelog.Debian.gz is in libfastjet-dev 3.0.6+dfsg-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libfastjet-dev/../libfastjet0/changelog.Debian.gz
/usr/share/doc/libfastjet-dev/../libfastjet0/changelog.Debian.gz