code: function patchScopedSlots (instance) {
    if (!instance._u) return
    // https://github.com/vuejs/vue/blob/dev/src/core/instance/render-helpers/resolve-scoped-slots.js
    const original = instance._u
    instance._u = slots => {
      try {
        // 2.6.4 ~ 2.6.6
        return original(slots, true)
      } catch (e) {
        // 2.5 / >= 2.6.7
        return original(slots, null, true)
      }
    }
    return () => {
      instance._u = original
    }
  }
docs: 2.6 optimizes template-compiled scoped slots and skips updates if child only uses scoped slots. We need to patch the scoped slots resolving helper to temporarily mark all scoped slots as unstable in order to force child updates.