Status code is ignored when response payload is empty

This will return the statusCode `200` but I expect `401`. This can be fixed when I pass an empty response body like `[401, '']`. It this the desired bahviour?
```js
    const verifyPublishedContentMock = Nock(callbackUrl)
      .post('/')
      .query(true)
      .reply(function(uri, requestBody) {
        return [401]
      })
```