Disband them. If there's nothing left for the workers to do, they aren't much use. Keep a couple around for repairs, or if you start conquering fresh land. OR, If you don't want to disband them, and you're at war, try using them as bait to draw AI units into less defensive positions. No shields, unfortunately. And no way to add domestic units to your cities. I kinda miss these features, but at least we can't abuse them now.