Comment 1 for bug 1744920

[root@nail-5300-2 oslo_service]# /usr/bin/python2 /usr/bin/nova-compute
> /usr/lib/python2.7/site-packages/eventlet/hubs/__init__.py(115)get_hub()
-> try:
(Pdb) c
> /usr/lib/python2.7/site-packages/eventlet/hubs/__init__.py(70)use_hub()
-> if mod is None:
(Pdb) w
  /usr/bin/nova-compute(6)<module>()
-> from nova.cmd.compute import main
  /usr/lib/python2.7/site-packages/nova/cmd/compute.py(28)<module>()
-> from nova.cmd import common as cmd_common
  /usr/lib/python2.7/site-packages/nova/cmd/common.py(28)<module>()
-> import nova.conf
  /usr/lib/python2.7/site-packages/nova/conf/__init__.py(27)<module>()
-> from nova.conf import cinder
  /usr/lib/python2.7/site-packages/nova/conf/cinder.py(16)<module>()
-> from keystoneauth1 import loading as ks_loading
  /usr/lib/python2.7/site-packages/keystoneauth1/loading/__init__.py(13)<module>()
-> from keystoneauth1.loading import adapter
  /usr/lib/python2.7/site-packages/keystoneauth1/loading/adapter.py(13)<module>()
-> from keystoneauth1 import adapter
  /usr/lib/python2.7/site-packages/keystoneauth1/adapter.py(18)<module>()
-> from keystoneauth1 import session
  /usr/lib/python2.7/site-packages/keystoneauth1/session.py(26)<module>()
-> import requests
  /usr/lib/python2.7/site-packages/requests/__init__.py(52)<module>()
-> from .packages.urllib3.contrib import pyopenssl
  /usr/lib/python2.7/site-packages/requests/packages/__init__.py(27)<module>()
-> from . import urllib3
  /usr/lib/python2.7/site-packages/requests/packages/urllib3/__init__.py(8)<module>()
-> from .connectionpool import (
  /usr/lib/python2.7/site-packages/requests/packages/urllib3/connectionpool.py(35)<module>()
-> from .connection import (
  /usr/lib/python2.7/site-packages/requests/packages/urllib3/connection.py(44)<module>()
-> from .util.ssl_ import (
  /usr/lib/python2.7/site-packages/requests/packages/urllib3/util/__init__.py(3)<module>()
-> from .connection import is_connection_dropped
  /usr/lib/python2.7/site-packages/requests/packages/urllib3/util/connection.py(144)<module>()
-> HAS_IPV6 = _has_ipv6('::1')
  /usr/lib/python2.7/site-packages/requests/packages/urllib3/util/connection.py(134)_has_ipv6()
-> sock = socket.socket(socket.AF_INET6)
  /usr/lib/python2.7/site-packages/eventlet/greenio/base.py(133)__init__()
-> notify_opened(fd.fileno())
  /usr/lib/python2.7/site-packages/eventlet/hubs/__init__.py(193)notify_opened()
-> hub = get_hub()
  /usr/lib/python2.7/site-packages/eventlet/hubs/__init__.py(115)get_hub()
-> try:
> /usr/lib/python2.7/site-packages/eventlet/hubs/__init__.py(70)use_hub()
-> if mod is None:
(Pdb) os.environ['EVENTLET_HUB']
*** KeyError: 'EVENTLET_HUB'
(Pdb)

os.environ['EVENTLET_HUB'] should be 'oslo_service:service_hub' when get_hub function was used for the first time.