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.
revealOrder: SuspenseListRevealOrder,
) {
  if (__DEV__) {
    if (Mode !== undefined && !didWarnAboutTailOptions[Mode]) {
      if (Mode !== 'collapsed' && Mode !== 'hidden') {
        didWarnAboutTailOptions[Mode] = true;
        console.error(
          '"%s" is not a supported value for  on <SuspenseList />. ' +
            'Did you mean "collapsed" or "hidden"?',
          Mode,
        );
      } else if (revealOrder !== 'forwards' && revealOrder !== 'backwards') {
        didWarnAboutTailOptions[Mode] = true;
        console.error(
          '<SuspenseList ="%s" /> is only valid if revealOrder is ' +
            '"forwards" or "backwards". ' +
            'Did you mean to specify revealOrder="forwards"?',
          Mode,
        );
      }
    }
  }
}
function validateSuspenseListNestedChild(childSlot: mixed, index: number) {
  if (__DEV__) {
    const isArray = Array.isArray(childSlot);
    const isIterable =
      !isArray && typeof getIteratorFn(childSlot) === 'function';
    if (isArray || isIterable) {
      const type = isArray ? 'array' : 'iterable';