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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

advanceTimeBy(20); 
        renderer.update(
          <React.unstable_Profiler id="two" onRender={callback}>
            <AdvanceTime byAmount={1} />
          </React.unstable_Profiler>,
        );
        expect(callback).toHaveBeenCalledTimes(2);
        const [mountCall, updateCall] = callback.mock.calls;
        expect(mountCall[0]).toBe('one');
        expect(mountCall[1]).toBe('mount');
        expect(mountCall[2]).toBe(2); 
        expect(mountCall[3]).toBe(2); 
        expect(mountCall[4]).toBe(5); 
        expect(updateCall[0]).toBe('two');
        expect(updateCall[1]).toBe('update');
        expect(updateCall[2]).toBe(1); 
        expect(updateCall[3]).toBe(1); 
        expect(updateCall[4]).toBe(27); 
      });
      it('should not be called until after mutations', () => {
        let classComponentMounted = false;
        const callback = jest.fn(
          (id, phase, actualDuration, baseDuration, startTime, commitTime) => {
            
            expect(classComponentMounted).toBe(true);
            
            expect(commitTime).toBe(2);
          },
        );
        class ClassComponent extends React.Component {