The side faces of wall signs do not get culled against blocks

As of snapshot 7, signs are now handled via the block model system. If placed on a wall, the left and right faces are flush with blocks, and an adjacent block occludes this face entirely. However, the face is still rendered, unlike most such blocks which correctly have a cullface argument to remove this quad from the chunk mesh, saving on performance.

Expected outcome would be for this face to not render, as there is no need for it to. Easily achieved via a cullface argument on the template model.