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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(['Yield:5']);
          
          
          expect(callback).toHaveBeenCalledTimes(1);
          let call = callback.mock.calls[0];
          expect(call[2]).toBe(5); 
          expect(call[3]).toBe(5); 
          expect(call[4]).toBe(115); 
          expect(call[5]).toBe(120); 
          callback.mockReset();
          
          expect(renderer).toFlushWithoutYielding();
          expect(callback).toHaveBeenCalledTimes(0);
        });
        it('should report the expected times when a high-priority update replaces a low-priority update', () => {
          const callback = jest.fn();
          const Yield = ({renderTime}) => {
            advanceTimeBy(renderTime);
            ReactTestRenderer.unstable_yield('Yield:' + renderTime);
            return null;
          };
          advanceTimeBy(5); 
          const renderer = ReactTestRenderer.create(
            <React.unstable_Profiler id="test" onRender={callback}>
              <Yield renderTime={6} />
              <Yield renderTime={15} />
            </React.unstable_Profiler>,
            {unstable_isConcurrent: true},
          );