In an application with an entry point of __main__.py, multiprocessing.Pool throws the following:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "D:\Dev\Python27\lib\multiprocessing\forking.py", line 346, in main
    prepare(preparation_data)
  File "D:\Dev\Python27\lib\multiprocessing\forking.py", line 454, in prepare
    assert main_name not in sys.modules, main_name
AssertionError: __main__

These messages repeat as long as the application is running.

Demonstration Code, must be in file named __main__.py:
--------------------
import multiprocessing
import time

if __name__ == '__main__':
    pool = multiprocessing.Pool()
    time.sleep(2)
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