Sandbox: https://codesandbox.io/s/cranky-kapitsa-op3jh

Repro: type "a" and then after a second "b"

Expected: Eventually you'll see "ab" in all fields. Pending "..." indicator goes away.

Actual: You'll keep seeing "a" in low pri field. Pending "..." indicator is stuck.
reducer: (S, A) => S,
      initialArg: I,
      init?: I => S,
    ): [S, Dispatch<A>] {
      currentHookNameInDev = 'useReducer';
      warnInvalidHookAccess();
      updateHookTypesDev();
      const prevDispatcher = ReactCurrentDispatcher.current;
      ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnUpdateInDEV;
      try {
        return updateReducer(reducer, initialArg, init);
      } finally {
        ReactCurrentDispatcher.current = prevDispatcher;
      }
    },
    useRef<T>(initialValue: T): {|current: T|} {
      currentHookNameInDev = 'useRef';
      warnInvalidHookAccess();
      updateHookTypesDev();
      return updateRef(initialValue);
    },
    useState<S>(
      initialState: (() => S) | S,
    ): [S, Dispatch<BasicStateAction<S>>] {
      currentHookNameInDev = 'useState';
      warnInvalidHookAccess();
      updateHookTypesDev();
      const prevDispatcher = ReactCurrentDispatcher.current;
      ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnUpdateInDEV;
      try {