Repro case with a master build: https://codesandbox.io/s/stoic-mcnulty-dhygf?file=/src/App.js:668-703

Expected: we see content after a second.
Actual: fallback never resolves.

This happens in a sequence of:

1. Normal update
   - which suspends
2. Idle update
   - which also suspends
3. An unrelated normal update immediately followed by a ping (so they're batched)
   - here, we decide to stay on fallback, but should've shown the content

If you remove `_setVersion(v => v + 1);` on line 44 then the issue goes away.
ReactNoop.expire(4999);
    expect(Scheduler).toFlushWithoutYielding();
    expect(ReactNoop.getChildren()).toEqual([span('S')]);
    
    React.unstable_withSuspenseConfig(
      () => ReactNoop.render(<App text="B" />),
      {
        timeoutMs: 10000,
      },
    );
    
    expect(Scheduler).toFlushAndYield(['Suspend! [B]', 'Loading...']);
    expect(ReactNoop.getChildren()).toEqual([span('S')]);
    
    
    ReactNoop.render(<App text="C" />);
    expect(Scheduler).toFlushAndYield(['C']);
    expect(ReactNoop.getChildren()).toEqual([span('C')]);
    await advanceTimers(10000);
    
    expect(Scheduler).toHaveYielded([
      'Promise resolved [A]',
      'Promise resolved [B]',
    ]);
    
    expect(Scheduler).toFlushWithoutYielding();
    expect(ReactNoop.getChildren()).toEqual([span('C')]);
  });
  it('flushes all expired updates in a single batch', async () => {
    class Foo extends React.Component {