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.
Scheduler.unstable_advanceTime(1500);
    await advanceTimers(1500);
    expect(Scheduler).toFlushAndYield(['Suspend! [A]', 'Loading A...']);
    
    expect(ReactNoop.getChildren()).toEqual([]);
    
    Scheduler.unstable_runWithPriority(Scheduler.unstable_IdlePriority, () =>
      ReactNoop.render(<Foo renderContent={2} />),
    );
    
    expect(Scheduler).toFlushAndYield([]);
    
    expect(ReactNoop.getChildren()).toEqual([]);
    
    Scheduler.unstable_advanceTime(150);
    await advanceTimers(150);
    
    expect(ReactNoop.getChildren()).toEqual([]);
    
    Scheduler.unstable_advanceTime(600);
    await advanceTimers(600);
    expect(ReactNoop.getChildren()).toEqual([span('Loading A...')]);
  });
  describe('delays transitions when there a suspense config is supplied', () => {
    const SUSPENSE_CONFIG = {
      timeoutMs: 2000,
    };
    
    it('top level render', async () => {
      function App({page}) {