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.
expect(Scheduler).toFlushAndYield(['Inner content']);
    expect(ReactNoop.getChildren()).toEqual([
      span('Sync'),
      span('Outer content'),
      span('Inner content'),
    ]);
  });
  it('renders an expiration boundary synchronously', async () => {
    spyOnDev(console, 'error');
    
    ReactNoop.flushSync(() =>
      ReactNoop.render(
        <Fragment>
          <Suspense fallback={<Text text="Loading..." />}>
            <AsyncText text="Async" />
          </Suspense>
          <Text text="Sync" />
        </Fragment>,
      ),
    );
    expect(Scheduler).toHaveYielded([
      
      'Suspend! [Async]',
      
      'Loading...',
      
      'Sync',
    ]);
    
    expect(ReactNoop.getChildren()).toEqual([span('Loading...'), span('Sync')]);