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="Initial" />);
    
    
    await ReactNoop.act(async () => {
      root.render(<App text="First update" />);
      expect(Scheduler).toFlushAndYield(['Suspend! [First update]']);
      
      expect(root).toMatchRenderedOutput(<span prop="Initial" />);
    });
    
    await ReactNoop.act(async () => {
      root.render(<App text="Second update" />);
      expect(Scheduler).toFlushAndYield(['Suspend! [Second update]']);
      
      expect(root).toMatchRenderedOutput(<span prop="Initial" />);
    });
  });
  it('regression test: resets current "debug phase" after suspending', async () => {
    function App() {
      return (
        <Suspense fallback="Loading...">
          <Foo suspend={false} />
        </Suspense>
      );
    }
    const thenable = {then() {}};
    let foo;
    class Foo extends React.Component {
      state = {suspend: false};
      render() {