/usr/share/doc/libgtksourceview-3.0-dev/changelog.Debian.gz is in libgtksourceview-3.0-dev 3.24.7-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgtksourceview-3.0-dev/../libgtksourceview-3.0-1/changelog.Debian.gz