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.
return (
        <Suspense fallback={<Text text="Loading..." />}>
          <Text text="Hi!" />
          {page === 'A' ? (
            <Text text="A" />
          ) : (
            <Suspense
              fallback={<Text text={'Loading ' + page + '...'} />}
              unstable_avoidThisFallback={true}>
              <AsyncText text={page} ms={3000} />
            </Suspense>
          )}
        </Suspense>
      );
    }
    
    ReactNoop.render(<App page="A" />);
    expect(Scheduler).toFlushAndYield(['Hi!', 'A']);
    expect(ReactNoop.getChildren()).toEqual([span('Hi!'), span('A')]);