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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

appendInitialChild,
  finalizeInitialChildren,
  prepareUpdate,
  supportsMutation,
  supportsPersistence,
  cloneInstance,
  cloneHiddenInstance,
  cloneUnhiddenInstance,
  createContainerChildSet,
  appendChildToContainerChildSet,
  finalizeContainerChildren,
} from './ReactFiberHostConfig';
import {
  getRootHostContainer,
  popHostContext,
  getHostContext,
  popHostContainer,
} from './ReactFiberHostContext';
import {
  isContextProvider as isLegacyContextProvider,
  popContext as popLegacyContext,
  popTopLevelContextObject as popTopLevelLegacyContextObject,
} from './ReactFiberContext';
import {popProvider} from './ReactFiberNewContext';
import {
  prepareToHydrateHostInstance,
  prepareToHydrateHostTextInstance,
  popHydrationState,
} from './ReactFiberHydrationContext';
function markUpdate(workInProgress: Fiber) {