The Menu class property 'container_tag_attrs' is used recursively. With Foundation the drilldown menu the 'data-drilldown' attribute goes on the root menu element. However container_tag_attrs places it on every container in the menu.
'container_tag_attrs' should be changed to behave similarly to 'subcontainer_tag_class', where it accepts an array of values to be applied at different nested depths. Where the 0 index is used on the root menu, 1 is used on the first nested container, 2 is used on the second nested container, and so on.