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.
console.error(
        'A nested %s was passed to row #%s in <SuspenseList />. Wrap it in ' +
          'an additional SuspenseList to configure its revealOrder: ' +
          '<SuspenseList revealOrder=...> ... ' +
          '<SuspenseList revealOrder=...>{%s}</SuspenseList> ... ' +
          '</SuspenseList>',
        type,
        index,
        type,
      );
      return false;
    }
  }
  return true;
}
function validateSuspenseListChildren(
  children: mixed,
  revealOrder: SuspenseListRevealOrder,
) {
  if (__DEV__) {
    if (
      (revealOrder === 'forwards' || revealOrder === 'backwards') &&
      children !== undefined &&
      children !== null &&
      children !== false
    ) {
      if (Array.isArray(children)) {
        for (let i = 0; i < length; i++) {
          if (!validateSuspenseListNestedChild(children[i], i)) {
            return;