devstack install attributeError: 'module' object has no attribute '__version__'

work around:

edit the file /usr/local/lib/python2.7/dist-packages/openstack/session.py and remove the .__version__ at line 29.

DEFAULT_USER_AGENT = "openstacksdk/%s" % openstack.__version__

DEFAULT_USER_AGENT = "openstacksdk/%s" % openstack

ref: https://ask.openstack.org/en/question/56412/juno-devstack-install-failure-attributeerror-module-object-has-no-attribute-wraps/