Multiprocessing Poolは、aply_を使用しています.async()時報が間違っています

Traceback (most recent call last):
  File "/usr/lib64/python2.7/threading.py", line 812, in __bootstrap_inner
    self.run()
  File "/usr/lib64/python2.7/threading.py", line 765, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib64/python2.7/multiprocessing/pool.py", line 342, in _handle_tasks
    put(task)
RuntimeError: dictionary changed size during iteration

https://bugs.python.org/issue23051