v-for render twice

[a1mersnow]

Version

3.0.0-rc.2

Reproduction link

https://github.com/aimergenge/reproduction-for-vue3

Steps to reproduce

1. clone the reproduction repo
2. use cd move into it
3. yarn
4. yarn dev

What is expected?

v-for is correctly rendered

What is actually happening?

v-for render twice

---

This is a very weird problem……

When you delete the scoped style block of App.vue, it works!
When you delete the comment in HelloWorld.vue's template block, it works!
When you delete the custom directive v-nothing in HelloWorld.vue, it works!
When you add v-if="data" to the container tag in HelloWorld.vue, it works!