Updated openstack/openstack
Project: openstack/nova  b57cc309bf3a93e46737ed3e2731dcf43ba76135

Added missing raise statement when checking the config driver format

Closes-bug: #1275772

(cherry-picked from commit 378c28a8c05d3943324b5a39edef947ed7a9f52a)

Change-Id: I636525d0272511d4192c43d18c56e867fb7514d8