multiple OpenStackConfig().get_one_cloud() calls fail when using OS_CLOUD

[Andrew Woodward]

with OS_CLOUD as an envvar or as an command arg multiple calls create an instance of OpenStackConfig and then call get_one_cloud() fail

$ python -i
Python 2.7.12 (default, Nov 19 2016, 06:48:10)
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import os_client_config as oscc
>>> cc = oscc.OpenStackConfig()
>>> cc.get_one_cloud()
<os_client_config.cloud_config.CloudConfig object at 0x7f94e06b5cd0>
>>> cc.get_one_cloud()
<os_client_config.cloud_config.CloudConfig object at 0x7f94e0610610>
>>> cc.get_one_cloud()
<os_client_config.cloud_config.CloudConfig object at 0x7f94e06afc10>
>>> cc.get_one_cloud()
<os_client_config.cloud_config.CloudConfig object at 0x7f94e0610390>
>>> c2 = oscc.OpenStackConfig()
>>> c2.get_one_cloud()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/os_client_config/config.py", line 1071, in get_one_cloud
    auth_plugin = loader.load_from_options(**config['auth'])
  File "/home/awoodward/.local/lib/python2.7/site-packages/keystoneauth1/loading/base.py", line 162, in load_from_options
    raise exceptions.MissingRequiredOptions(missing_required)
keystoneauth1.exceptions.auth_plugins.MissingRequiredOptions: Auth plugin requires parameters which were not given: auth_url

----

This works fine in the traditonal envvars openrc style.
This fails using clouds.yaml format
To further isolate, this also works if you explicitly call for cloud='name'

More debugging: https://gist.github.com/xarses/55e2517bd49903df2c5ec7ff5f697d74

basic pattern that I expected to work

$ export OS_CLOUD=cloud1
$ python -i

import os_client_config

sdk = os_client_config.make_sdk()
neutron = os_client_config.make_client('network')

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/465195
Committed: https://git.openstack.org/cgit/openstack/os-client-config/commit/?id=8235e0ce6cff00bfa84501865a3cf48511cdf2ec
Submitter: Jenkins
Branch: master

commit 8235e0ce6cff00bfa84501865a3cf48511cdf2ec
Author: Monty Taylor <email address hidden>
Date: Tue May 16 18:12:41 2017 -0500

    Keep a singleton to support multiple get_config calls

    We are destructive to os.environ in the OpenStackConfig constructor- so
    it really should only ever be called once. Make sure get_config does
    this.

    Change-Id: I279bdf68408a807ec18fba634df3769c9b8fc4dc
    Closes-Bug: #1691294

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/os-client-config 1.28.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/python-openstacksdk 0.10.0 release.