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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

root.nextScheduledRoot = null;
          firstScheduledRoot = lastScheduledRoot = null;
          break;
        } else if (root === firstScheduledRoot) {
          // 
          const next = root.nextScheduledRoot;
          firstScheduledRoot = next;
          lastScheduledRoot.nextScheduledRoot = next;
          root.nextScheduledRoot = null;
        } else if (root === lastScheduledRoot) {
          // 
          lastScheduledRoot = previousScheduledRoot;
          lastScheduledRoot.nextScheduledRoot = firstScheduledRoot;
          root.nextScheduledRoot = null;
          break;
        } else {
          previousScheduledRoot.nextScheduledRoot = root.nextScheduledRoot;
          root.nextScheduledRoot = null;
        }
        root = previousScheduledRoot.nextScheduledRoot;
      } else {
        if (remainingExpirationTime > highestPriorityWork) {
          // 
          highestPriorityWork = remainingExpirationTime;
          highestPriorityRoot = root;
        }
        if (root === lastScheduledRoot) {
          break;
        }
        if (highestPriorityWork === Sync) {