[issue20980] In multiprocessing.pool, ExceptionWithTraceback should derive from Exception

[Steven Myint]

New submission from Steven Myint:

In multiprocessing.pool, ExceptionWithTraceback is not derived from Exception. Thus when it is raised, we get the exception, "TypeError: exceptions must derive from BaseException". Attached is a patch that fixes this.

See below example traceback that prompted me to notice this:

Traceback (most recent call last):
  File "/Users/myint/Library/Python/3.4/bin/yolk", line 9, in <module>
    load_entry_point('yolk3k==0.7.3', 'console_scripts', 'yolk')()
  File "/Users/myint/Library/Python/3.4/lib/python/site-packages/yolk/cli.py", line 1123, in main
    my_yolk.run()
  File "/Users/myint/Library/Python/3.4/lib/python/site-packages/yolk/cli.py", line 208, in run
    return getattr(self, action)()
  File "/Users/myint/Library/Python/3.4/lib/python/site-packages/yolk/cli.py", line 240, in show_updates
    for (project_name, version, newest) in _updates(pkg_list, self.pypi):
  File "/Users/myint/Library/Python/3.4/lib/python/site-packages/yolk/cli.py", line 1104, in _updates
    names):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/pool.py", line 255, in map
    return self._map_async(func, iterable, mapstar, chunksize).get()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/pool.py", line 594, in get
    raise self._value
TypeError: exceptions must derive from BaseException

----------
components: Library (Lib)
files: exception_with_traceback.diff
keywords: patch
messages: 214101
nosy: myint
priority: normal
severity: normal
status: open
title: In multiprocessing.pool, ExceptionWithTraceback should derive from Exception
type: behavior
versions: Python 3.4
Added file: http://bugs.python.org/file34518/exception_with_traceback.diff

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<http://bugs.python.org/issue20980>
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