Nested `startTransition` call "takes over" and makes parent `startTransition` unable to track `isPending`.

Seb says it's a bug.

Repro:

https://codesandbox.io/s/pensive-breeze-rg70wn?file=/IndexPage.js:192-288

1. Click the button
2. `isPending` in `IndexPage.js` is `true`

However, `isPending` in `App.js` is `false`.

Expected: `isPending` in `App.js` is also `true`.
const newQueueLanes = mergeLanes(queueLanes, lane);
    queue.lanes = newQueueLanes;
    
    
    
    markRootEntangled(root, newQueueLanes);
  }
}
function markUpdateInDevTools<A>(fiber: Fiber, lane: Lane, action: A): void {
  if (__DEV__) {
    if (enableDebugTracing) {
      if (fiber.mode & DebugTracingMode) {
        const name = getComponentNameFromFiber(fiber) || 'Unknown';
        logStateUpdateScheduled(name, lane, action);
      }
    }
  }
  if (enableSchedulingProfiler) {
    markStateUpdateScheduled(fiber, lane);
  }
}
export const ContextOnlyDispatcher: Dispatcher = {
  readContext,
  useCallback: throwInvalidHookError,
  useContext: throwInvalidHookError,
  useEffect: throwInvalidHookError,
  useImperativeHandle: throwInvalidHookError,
  useInsertionEffect: throwInvalidHookError,
  useLayoutEffect: throwInvalidHookError,