Override the method to change the form attribute empty_permitted.

def _construct_form(self, i, **kwargs):
        """Override the method to change the form attribute empty_permitted."""
        form = super(MetadataFormset, self)._construct_form(i, **kwargs)
        # Monkey patch the form to always force a save.
        # It's unfortunate, but necessary because we always want an instance
        # Affect on performance shouldn't be too great, because ther is only
        # ever one metadata attached
        form.empty_permitted = False
        form.has_changed = lambda: True

        # Set a marker on this object to prevent automatic metadata creation
        # This is seen by the post_save handler, which then skips this
        # instance.
        if self.instance:
            self.instance.__seo_metadata_handled = True

        return form