Slot testing fails for component.

[trashpanda001]

Version

1.0.0-beta.21

Reproduction link

https://github.com/sickp/vue-test-slots

Steps to reproduce

yarn install
yarn test:unit

What is expected?

• named slot "header" to receive 'Hello There'
• default slot to receive 'Content Goes Here'

What is actually happening?

default slot receives 'Hello There'

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This worked in 1.0.0-beta.20

[bost-h]

It does not seem related to functional components to me, it also fails when the component is not functional.
It think it comes from createSlotVNodes https://github.com/vuejs/vue-test-utils/blob/dev/packages/create-instance/create-slot-vnodes.js#L41 which receive good values, but returns an array with duplicated VNodes. It looks like a reference/value issue, where VNodes having already been created are overwritten by the creation of a new VNode