plone/plone.app.contentlisting — pull request #1 by gaudenz (2012-02-09 13:48:50+00:00)
Title: Return portal_type in ContentTypeClass

Change ContentTypeClass to return contenttype-{portal_type} to match
what the rest of Plone expects. This fixes sprite based content icons
for documents/pages.

I ran bin/alltests with this change and no tests broke. But as I'm not sure about the reasons why this was made to differ from the rest of plone I'm sending this as a pull request.