The attached test program calls apply_async with a function that will raise CalledProcessError. However, when result.get() is called, it raises a TypeError and the program hangs:

$ ./bug.py
ERROR:root:ops
Traceback (most recent call last):
  File "./bug.py", line 19, in run_with
    dW1 = run_dcon()
  File "./bug.py", line 26, in run_dcon
    subprocess.check_call(['dcon'], stdout=fh, stderr=fh)
  File "/usr/lib/python2.6/subprocess.py", line 498, in check_call
    raise CalledProcessError(retcode, cmd)
CalledProcessError: Command '['dcon']' returned non-zero exit status 127
Exception in thread Thread-2:
Traceback (most recent call last):
  File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.6/threading.py", line 484, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib/python2.6/multiprocessing/pool.py", line 259, in _handle_results
    task = get()
TypeError: ('__init__() takes exactly 3 arguments (1 given)', <class 'subprocess.CalledProcessError'>, ())