Comment 5 for bug 1457100

I encountered this problem as well. It installs novaclient without any issue, but then when you use it, it will throw the above error message.

For the following requirements pip will install pbr 1.0.1
novaclient requirements [1]: pbr>=0.11,<2.0
oslo.config requirements [2]: pbr>=0.6,!=0.7,<1.0

[1]: https://github.com/openstack/python-novaclient/blob/2.25.0/requirements.txt
[2]: https://github.com/openstack/oslo.config/blob/1.11.0/requirements.txt