test_execute_with_preexec_fn failed on Python 3.5

[ChangBo Guo(gcb)]

Got error recently as follow on Python 3.5 unit test CI job:

ft1.5: oslo_concurrency.tests.unit.test_processutils.UtilsTest.test_execute_with_preexec_fn_StringException: Empty attachments:
  stderr
  stdout

Traceback (most recent call last):
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/oslo_concurrency/tests/unit/test_processutils.py", line 120, in test_execute_with_preexec_fn
    preexec_fn=preexec_fn)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/testcase.py", line 485, in assertRaises
    self.assertThat(our_callable, matcher)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/testcase.py", line 496, in assertThat
    mismatch_error = self._matchHelper(matchee, matcher, message, verbose)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/testcase.py", line 547, in _matchHelper
    mismatch = matcher.match(matchee)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/matchers/_exception.py", line 108, in match
    mismatch = self.exception_matcher.match(exc_info)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/matchers/_higherorder.py", line 62, in match
    mismatch = matcher.match(matchee)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/testcase.py", line 475, in match
    reraise(*matchee)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/_compat3x.py", line 16, in reraise
    raise exc_obj.with_traceback(exc_tb)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/matchers/_exception.py", line 101, in match
    result = matchee()
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/testtools/testcase.py", line 1049, in __call__
    return self._callable_object(*self._args, **self._kwargs)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/oslo_concurrency/processutils.py", line 374, in execute
    env=env_variables)
  File "/home/jenkins/workspace/gate-oslo.concurrency-python35/.tox/py35/lib/python3.5/site-packages/eventlet/green/subprocess.py", line 55, in __init__
    subprocess_orig.Popen.__init__(self, args, 0, *argss, **kwds)
  File "/usr/lib/python3.5/subprocess.py", line 947, in __init__
    restore_signals, start_new_session)
  File "/usr/lib/python3.5/subprocess.py", line 1552, in _execute_child
    raise child_exception_type(err_msg)
subprocess.SubprocessError: Exception occurred in preexec_fn.

[ChangBo Guo(gcb) (glongwave)]

Fix in https://review.openstack.org/#/c/478891/

[Yuriy Taraday (yorik-sar)]

Upstream issue: https://github.com/eventlet/eventlet/issues/413 - eventlet makes a hidden reimport of subprocess module before inheriting from subprocess.Popen causing all exceptions raised from it becoming uncatchable.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/oslo.concurrency 3.21.0 release.