Sporadic test_popen_communicate failure on py3k

[fmoo]

Saw this when pushing 0.7.0 to github. identical master build passed.

Failure logs as follows:

____________________ TestSelectTask.test_popen_communicate _____________________

self = <tests.tasks.test_select.TestSelectTask testMethod=test_popen_communicate>

    def test_popen_communicate(self):
        future = self.task.popen_communicate(
            'echo hello', shell=True)
>       result = future.result(3.0)

tests/tasks/test_select.py:89:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/opt/python/3.3.5/lib/python3.3/concurrent/futures/_base.py:401: in result
    return self.__get_result()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <Future at 0x7f6e92d802d0 state=finished raised ProcessFailed>

    def __get_result(self):
        if self._exception:
>           raise self._exception
E sparts.tasks.select.ProcessFailed: ('hello\n', '', None)
/opt/python/3.3.5/lib/python3.3/concurrent/futures/_base.py:353: ProcessFailed
----------------------------- Captured stderr call -----------------------------
DEBUG:TestService:All tasks started
DEBUG:TestService:VService Active. Awaiting graceful shutdown.
INFO:TestService:Waiting for tasks to shutdown gracefully...
DEBUG:TestService:Waiting for <sparts.tasks.select.SelectTask object at 0x7f6e92d80090> to stop...
DEBUG:TestService.SelectTask:Thread SelectTask exited