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.
return {type: 'span', children: [], prop, hidden: false};
  }
  function hiddenSpan(prop) {
    return {type: 'span', children: [], prop, hidden: true};
  }
  function advanceTimers(ms) {
    
    
    if (typeof ms !== 'number') {
      throw new Error('Must specify ms');
    }
    jest.advanceTimersByTime(ms);
    
    
    return Promise.resolve().then(() => {});
  }
  function Text(props) {