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.
setOuterText(text);
      setInnerText(text);
    }
    
    await resolveText('Inner: A0');
    await ReactNoop.act(async () => {
      root.render(<Parent step={0} />);
    });
    expect(Scheduler).toHaveYielded(['Outer: A0', 'Inner: A0', 'Commit Child']);
    expect(root).toMatchRenderedOutput(
      <>
        <span prop="Outer: A0" />
        <span prop="Inner: A0" />
      </>,
    );
    
    await ReactNoop.act(async () => {
      setText('B');
    });
    expect(Scheduler).toHaveYielded([
      'Outer: B0',
      'Suspend! [Inner: B0]',
      'Loading...',
    ]);
    
    await advanceTimers(250);
    expect(root).toMatchRenderedOutput(
      <>
        <span prop="Outer: B0" />
        <span hidden={true} prop="Inner: A0" />