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.
state = {page: 'none'};
        render() {
          transitionToPage = page => this.setState({page});
          const page = this.state.page;
          if (page === 'none') {
            return null;
          }
          return (
            <Suspense fallback={<Text text="Loading..." />}>
              <AsyncText text={page} ms={5000} />
            </Suspense>
          );
        }
      }
      ReactNoop.render(<App />);
      expect(Scheduler).toFlushAndYield([]);
      
      await ReactNoop.act(async () => {
        React.unstable_withSuspenseConfig(
          () => transitionToPage('A'),
          SUSPENSE_CONFIG,
        );
        expect(Scheduler).toFlushAndYield(['Suspend! [A]', 'Loading...']);
        
        Scheduler.unstable_advanceTime(400);
        await advanceTimers(400);
        expect(ReactNoop.getChildren()).toEqual([span('Loading...')]);