We added a new matches helper to our cards, page template scripts, and layouts/html.hbs, to ease with upgrading from a single language site to a multi-language site (particularly when a user had specified relative urls in those files).
Upgrade Implications: If you overrode your core.hbs, but did not override all of your cards, page template scripts and the layouts/html.hbs file, your site will not function. We’d recommend refreshing the core.hbs file to get the new helper.