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(root).toMatchRenderedOutput(<span prop="B" />);
      
      await ReactNoop.act(async () => {
        setText('C');
      });
      expect(Scheduler).toHaveYielded(['Suspend! [C]', 'Loading...']);
      
      
      await ReactNoop.act(async () => {
        await advanceTimers(250);
      });
      
      
      
      expect(root).toMatchRenderedOutput(
        <>
          <span hidden={true} prop="B" />
          <span prop="Loading..." />
        </>,
      );
      await ReactNoop.act(async () => {
        
        setText('D');
        
        await resolveText('E');
        Scheduler.unstable_runWithPriority(
          Scheduler.unstable_IdlePriority,
          () => {
            setText('E');
          },