Yoast/wordpress-seo — pull request #920 by lgrandicelli (2014-03-22 12:18:17+00:00)
Title: Fixed Open Graph Facebook Debubber Tags/Categories Issue

As seen on http://www.lucagrandicelli.com/2014/03/21/fix-open-graph-tag-issue-using-wordpress-seo-yoast/
This fix resolves the annoying issue of a warning message, when checking for Open Graph validation on the Facebook Debugger Tool.