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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

value = new Error(
      (getComponentName(sourceFiber.type) || 'A React component') +
        ' suspended while rendering, but no fallback UI was specified.\n' +
        '\n' +
        'Add a <Suspense fallback=...> component higher in the tree to ' +
        'provide a loading indicator or placeholder to display.' +
        getStackByFiberInDevAndProd(sourceFiber),
    );
  }
  
  
  
  renderDidError();
  value = createCapturedValue(value, sourceFiber);
  let workInProgress = returnFiber;
  do {
    switch (workInProgress.tag) {
      case HostRoot: {
        const errorInfo = value;
        workInProgress.effectTag |= ShouldCapture;
        workInProgress.expirationTime = renderExpirationTime;
        const update = createRootErrorUpdate(
          workInProgress,
          errorInfo,
          renderExpirationTime,
        );
        enqueueCapturedUpdate(workInProgress, update);
        return;
      }
      case ClassComponent: