/usr/share/doc/sat-xmpp-primitivus/changelog.Debian.gz is in sat-xmpp-primitivus 0.6.1.1+hg20180208-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/sat-xmpp-primitivus/../sat-xmpp-core/changelog.Debian.gz