[Queens][promotion] ImportError: cannot import name test neutron tempest plugin

[chandan kumar]

Queens promotion job is broken due to following errors in following jobs:
TEMPESTDATA=/home/zuul
2019-08-09 07:18:18 | + /usr/bin/tempest list-plugins
2019-08-09 07:18:20 | +----------------+------------------------------------------------------+
2019-08-09 07:18:20 | | Name | EntryPoint |
2019-08-09 07:18:20 | +----------------+------------------------------------------------------+
2019-08-09 07:18:20 | | neutron_tests | neutron_tempest_plugin.plugin:NeutronTempestPlugin |
2019-08-09 07:18:20 | | keystone_tests | keystone_tempest_plugin.plugin:KeystoneTempestPlugin |
2019-08-09 07:18:20 | +----------------+------------------------------------------------------+
2019-08-09 07:18:20 | + /usr/bin/tempest run --whitelist_file=/home/zuul/whitelist_file.conf --blacklist_file=/home/zuul/skip_file --concurrency 4
2019-08-09 07:18:25 |
2019-08-09 07:18:25 | =========================
2019-08-09 07:18:25 | Failures during discovery
2019-08-09 07:18:25 | =========================
2019-08-09 07:18:25 | --- import errors ---
2019-08-09 07:18:25 | Failed to import test module: neutron_tempest_plugin.bgpvpn.scenario.test_bgpvpn_basic
2019-08-09 07:18:25 | Traceback (most recent call last):
2019-08-09 07:18:25 | File "/usr/lib/python2.7/site-packages/unittest2/loader.py", line 445, in _find_test_path
2019-08-09 07:18:25 | module = self._get_module_from_name(name)
2019-08-09 07:18:25 | File "/usr/lib/python2.7/site-packages/unittest2/loader.py", line 384, in _get_module_from_name
2019-08-09 07:18:25 | __import__(name)
2019-08-09 07:18:25 | File "/usr/lib/python2.7/site-packages/neutron_tempest_plugin/bgpvpn/scenario/test_bgpvpn_basic.py", line 20, in <module>
2019-08-09 07:18:25 | from neutron_lib.utils import test
2019-08-09 07:18:25 | ImportError: cannot import name test
2019-08-09 07:18:25 |
2019-08-09 07:18:25 | ================================================================================
2019-08-09 07:18:25 | The above traceback was encountered during test discovery which imports all the found test modules in the specified test_path.

Below is the list of affected jobs:
* https://logs.rdoproject.org/openstack-periodic-24hr/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-7-ovb-3ctlr_1comp-featureset001-queens/9bb8452/logs/undercloud/home/zuul/tempest.log.txt.gz#_2019-08-09_07_18_25

* https://logs.rdoproject.org/openstack-periodic-24hr/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-7-multinode-1ctlr-featureset010-queens/0d12e3f/logs/undercloud/home/zuul/tempest.log.txt.gz#_2019-08-09_07_41_33

* https://logs.rdoproject.org/openstack-periodic-24hr/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-7-ovb-3ctlr_1comp-featureset035-queens/e72a358/logs/undercloud/home/zuul/tempest.log.txt.gz#_2019-08-09_07_07_16

* https://logs.rdoproject.org/openstack-periodic-24hr/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-7-ovb-1ctlr_2comp-featureset020-queens/570eee2/logs/undercloud/home/zuul/tempest.log.txt.gz#_2019-08-09_07_17_52

Root cause: https://review.rdoproject.org/r/#/c/21603/ causes the issue.

[chandan kumar (chkumar246)]

Fix proposed here: https://review.rdoproject.org/r/#/c/21784/