keras: Multiprocessing using fit_generator(pickle_safe=True) fails

I’m trying to use fit_generator to seperate data loader from trainer.

model.fit_generator(data_gen(), samples_per_epoch=10000, nb_epoch=1, pickle_safe=True, verbose=0)

Excuting this code produces error like below:

Traceback (most recent call last):
  File "main_generator.py", line 138, in <module>
    model.fit_generator(data_gen(), samples_per_epoch=10000, nb_epoch=1, pickle_safe=True, verbose=0)
  File "C:\dev\WinPython-64bit-3.5.2.3Qt5\python-3.5.2.amd64\lib\site-packages\keras\models.py", line 935, in fit_generator
    initial_epoch=initial_epoch)
  File "C:\dev\WinPython-64bit-3.5.2.3Qt5\python-3.5.2.amd64\lib\site-packages\keras\engine\training.py", line 1470, in fit_generator
    pickle_safe=pickle_safe)
  File "C:\dev\WinPython-64bit-3.5.2.3Qt5\python-3.5.2.amd64\lib\site-packages\keras\engine\training.py", line 436, in generator_queue
    thread.start()
  File "C:\dev\WinPython-64bit-3.5.2.3Qt5\python-3.5.2.amd64\lib\multiprocessing\process.py", line 105, in start
    self._popen = self._Popen(self)
  File "C:\dev\WinPython-64bit-3.5.2.3Qt5\python-3.5.2.amd64\lib\multiprocessing\context.py", line 212, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "C:\dev\WinPython-64bit-3.5.2.3Qt5\python-3.5.2.amd64\lib\multiprocessing\context.py", line 313, in _Popen
    return Popen(process_obj)
  File "C:\dev\WinPython-64bit-3.5.2.3Qt5\python-3.5.2.amd64\lib\multiprocessing\popen_spawn_win32.py", line 66, in __init__
    reduction.dump(process_obj, to_child)
  File "C:\dev\WinPython-64bit-3.5.2.3Qt5\python-3.5.2.amd64\lib\multiprocessing\reduction.py", line 59, in dump
    ForkingPickler(file, protocol).dump(obj)
AttributeError: Can't pickle local object 'generator_queue.<locals>.data_generator_task'

I also tried to test keras/tests/keras/test_multiprocessing.py, but it failed.

Here is output for test_multiprocessing.py: test_multiprocessing.faillog.txt

Is it bug of Keras itself? Any fixes available?