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.
'Loading more...',
      'Loading...',
    ]);
    expect(ReactNoop.getChildren()).toEqual([span('Loading...')]);
    
    Scheduler.unstable_advanceTime(250);
    await advanceTimers(250);
    expect(Scheduler).toHaveYielded(['Promise resolved [A]']);
    
    expect(Scheduler).toFlushAndYield([
      'A',
      
      'Suspend! [B]',
      'Loading more...',
    ]);
    
    
    expect(ReactNoop.getChildren()).toEqual([span('Loading...')]);
    Scheduler.unstable_advanceTime(200);
    await advanceTimers(200);
    
    expect(Scheduler).toHaveYielded(['Promise resolved [B]']);
    
    expect(ReactNoop.getChildren()).toEqual([span('Loading...')]);
    
    expect(Scheduler).toFlushAndYield(['A', 'B']);
    expect(ReactNoop.getChildren()).toEqual([span('A'), span('B')]);
  });
  it('does not suspend for very long after a higher priority update', async () => {
    function Foo({renderContent}) {