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_yieldValue('Foo');
      return (
        <Suspense
          unstable_avoidThisFallback={true}
          fallback={<Text text="Loading A..." />}>
          <Text text="A" />
          <Suspense
            unstable_avoidThisFallback={true}
            fallback={<Text text="Loading B..." />}>
            <AsyncText text="B" ms={5000} />
          </Suspense>
        </Suspense>
      );
    }
    ReactNoop.render(<Foo />);
    expect(Scheduler).toFlushAndYield([
      'Foo',
      'A',
      'Suspend! [B]',
      'Loading B...',
    ]);
    
    Scheduler.unstable_advanceTime(600);
    await advanceTimers(600);
    expect(ReactNoop.getChildren()).toEqual([span('A'), span('Loading B...')]);
  });
  it('keeps showing an avoided parent fallback if it is already showing', async () => {
    function Foo({showB}) {