If anyone is using action=parse with prop=modules and not including either jsconfigvars or encodedjsconfigvars in the prop parameter, you will start receiving a warning suggesting you do so.

Also, action=expandtemplates will now have prop=modules, jsconfigvars, and encodedjsconfigvars available.

This change should be deployed to WMF wikis with 1.26wmf9, see https://www.mediawiki.org/wiki/MediaWiki_1.26/Roadmap for the schedule.