#1661 introduced copying of passed options to parent wrapper. However it fails in a weird way if you are using data option for mount/shallowMount with external variable.

i.e.

    const defaultData = { foo: 3 }
    const wrapper = mountingMethod(TestComponent, { data: () => defaultData })

In this case data function will be invoked two times:

• one for Parent component (wrapper for our TestComponent) - at this point defaultData will be "poisoned" (will become reactive, and observed by Parent component for changes)
• one when Parent wrapper will be mounted, causing TestComponent instance to mount - at this point Vue will complain

[Vue warn]: Avoid adding reactive properties to a Vue instance or its root $data at runtime - declare it upfront in the data option.

because defaultData is treated as $data for Parent wrapper component already

In general, we do not need setting data on parent wrapper, so I just eliminate this propety before copying

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