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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

switch (ReactCurrentFiber.phase) {
      case 'getChildContext':
        if (didWarnSetStateChildContext) {
          return;
        }
        warningWithoutStack(
          false,
          'setState(...): Cannot call setState() inside getChildContext()',
        );
        didWarnSetStateChildContext = true;
        break;
      case 'render':
        if (didWarnAboutStateTransition) {
          return;
        }
        warningWithoutStack(
          false,
          'Cannot update during an existing state transition (such as within ' +
            '`render`). Render methods should be a pure function of props and state.',
        );
        didWarnAboutStateTransition = true;
        break;
    }
  };
}
let lastUniqueAsyncExpiration: number = Sync - 1;
let expirationContext: ExpirationTime = NoWork;
let isWorking: boolean = false;
let nextUnitOfWork: Fiber | null = null;
let nextRoot: FiberRoot | null = null;