As far as I understand the werk, it only adds checking for compatible versions. The compatibility itself should already be given in older versions as well.
Config master is pushing out to config slaves, so it makes sense to me to assume a 2.0 master’s config can not be understood by a 1.6 slave. But judging from the werk’s notes, a 2.0 slave can still handle the config sent by a 1.6 master.