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.
'Effect [B]',
      ]);
    } else {
      expect(Scheduler).toFlushAndYield([
        'B',
        'Destroy Layout Effect [Loading...]',
        'Destroy Effect [Loading...]',
        'Layout Effect [B]',
        'Effect [B]',
      ]);
    }
    
    ReactNoop.renderLegacySyncRoot(<App text="B2" />, () =>
      Scheduler.unstable_yieldValue('Commit root'),
    );
    expect(Scheduler).toHaveYielded([
      'A',
      'Suspend! [B2]',
      'C',
      'Loading...',
      
      
      'Layout Effect [Loading...]',
      'Commit root',
    ]);
    
    expect(Scheduler).toFlushAndYield([
      
      
      'Effect [Loading...]',