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.
'C',
        'Loading...',
        'Mount [A]',
        'Mount [B]',
        'Mount [C]',
        
        'Mount [Loading...]',
        'Commit root',
      ]);
      expect(ReactNoop).toMatchRenderedOutput(
        <>
          <span hidden={true} prop="A" />
          <span hidden={true} prop="C" />
          <span prop="Loading..." />
        </>,
      );
      ReactNoop.expire(1000);
      await advanceTimers(1000);
      expect(Scheduler).toHaveYielded(['Promise resolved [B]']);
      expect(Scheduler).toFlushExpired(['B']);
      expect(ReactNoop).toMatchRenderedOutput(
        <>
          <span prop="A" />
          <span prop="B" />
          <span prop="C" />
        </>,
      );
    });
    it('suspends inside constructor', async () => {
      class AsyncTextInConstructor extends React.Component {