The idea is that 2.5 is master today, but tomorrow, when 2.5.0 is released, we create a new "2.5" branch, and "master" now really becomes "2.6". So, we would actually remove the `versionadded` stuff from that new 2.5 branch. We could also do it in the other order, but typically Fabien would create the new branches, then we would go to work to update things on those new branches.