Scoped slot content doesn't update from array change

[KaelWD]

Version

2.6.7

Reproduction link

https://codepen.io/anon/pen/rROQJz?editors=1010

Steps to reproduce

Click the button next to "foo"

What is expected?

"bar 0" should be shown

What is actually happening?

"bar 1" is shown

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Original issue: vuetifyjs/vuetify#6643