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.
): [(() => void) => void, boolean],
  useMutableSource<Source, Snapshot>(
    source: MutableSource<Source>,
    getSnapshot: MutableSourceGetSnapshotFn<Source, Snapshot>,
    subscribe: MutableSourceSubscribeFn<Source, Snapshot>,
  ): Snapshot,
  useEvent(event: ReactListenerEvent): ReactListenerMap,
  useOpaqueIdentifier(): OpaqueIDType | void,
|};
type Update<S, A> = {|
  expirationTime: ExpirationTime,
  suspenseConfig: null | SuspenseConfig,
  action: A,
  eagerReducer: ((S, A) => S) | null,
  eagerState: S | null,
  next: Update<S, A>,
  priority?: ReactPriorityLevel,
|};
type UpdateQueue<S, A> = {|
  pending: Update<S, A> | null,
  dispatch: (A => mixed) | null,
  lastRenderedReducer: ((S, A) => S) | null,
  lastRenderedState: S | null,
|};
export type HookType =
  | 'useState'
  | 'useReducer'
  | 'useContext'
  | 'useRef'
  | 'useEffect'