`computed` returns a data trigger of the reference type that does not match the expectation

[huangmingfu]

(bug demo)

It should only perform the callback once initially, but it is also performed when the 'push' subitem is executed

When I run this code in the project, it works as expected, but playground refires every time I push it

The following actions should trigger the callback again：

<button @click="testArr = [{ label: '3', value: '3' }]">修改arr</button>