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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

this.componentDidCatch(error, {
        componentStack: stack !== null ? stack : '',
      });
      if (__DEV__) {
        if (typeof getDerivedStateFromError !== 'function') {
          
          
          
          warningWithoutStack(
            fiber.expirationTime === Sync,
            '%s: Error boundaries should implement getDerivedStateFromError(). ' +
              'In that method, return a state update to display an error message or fallback UI.',
            getComponentName(fiber.type) || 'Unknown',
          );
        }
      }
    };
  }
  return update;
}
function throwException(
  root: FiberRoot,
  returnFiber: Fiber,
  sourceFiber: Fiber,
  value: mixed,
  renderExpirationTime: ExpirationTime,
) {
  
  sourceFiber.effectTag |= Incomplete;