Mocking named slots is not working

[kieselsteini]

Version

1.0.0-beta.25

Reproduction link

https://github.com/kieselsteini/vue-named-slot-issue

Steps to reproduce

• yarn install
• yarn test:unit

What is expected?

• named slot "header" should contain "Hi, I am the header slot!"
• default slot should contain "Hi, I am the default slot!"

What is actually happening?

• default slot contains both

<div class="hello"><header></header> Hi, I am the default slot!Hi, I am the header slot!</div>