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**Do you want to request a *feature* or report a *bug*?**
bug, I believe, unless I misunderstand how it works
**What is the current behavior?**
Given a `Suspense` inside `Suspense` case like
```
<Suspense fallback="Fallback 1">
  <LazyText1 text="First text" />
  <Suspense fallback="Fallback 2">
    <LazyText2 text="Second text!" />
  </Suspense>
</Suspense>
```

Promises in `LazyTexts` start resolving at the same time, but if `LazyText2` is resolved first it never renders, `Fallback 2` stays.

Result:
```
First text

Fallback 2
```

Please see https://codesandbox.io/s/234o4zry7n

**What is the expected behavior?**

Every `LazyText` displayed in the end
```
First text

Second text!
```

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
react, react-dom 16.6.0

expect(ReactTestRenderer).toHaveYielded(['Loading...']);
    expect(root).toMatchRenderedOutput('Loading...');
    await LazyClass;
    expect(ReactTestRenderer).toHaveYielded(['Hi', 'Did mount: Hi']);
    expect(root).toMatchRenderedOutput('Hi');
  });
  it('only captures if `fallback` is defined', () => {
    const root = ReactTestRenderer.create(
      <Suspense fallback={<Text text="Loading..." />}>
        <Suspense maxDuration={100}>
          <AsyncText text="Hi" ms={5000} />
        </Suspense>
      </Suspense>,
      {
        unstable_isConcurrent: true,
      },
    );
    expect(root).toFlushAndYield([
      'Suspend! [Hi]',
      
      
      'Loading...',
    ]);
    jest.advanceTimersByTime(1000);
    expect(ReactTestRenderer).toHaveYielded([]);
    expect(root).toFlushAndYield([]);
    expect(root).toMatchRenderedOutput('Loading...');
    jest.advanceTimersByTime(5000);
    expect(ReactTestRenderer).toHaveYielded(['Promise resolved [Hi]']);
    expect(root).toFlushAndYield(['Hi']);