It seems that the fix for 13854 (http://bugs.python.org/issue13854) actually tried to solve 2 issues:

1. handle non-integer, non-string arg to SystemExit
2. use exit code of 0 when the arg was a string

The change involved for #2 seems to go against the documentation for sys.exit:

"...In particular, sys.exit("some error message") is a quick way to exit a program when an error occurs."

Indeed, python 2.7.5 appears to follow this behavior:

[me@localhost ~]$ python -c 'raise SystemExit("bye")'; echo $?
bye
1

Shouldn't the return code from a subprocess when using multiprocessing match the return code when called w/o the multiprocessing module?