+++ This bug was initially created as a clone of Bug #1575985 +++
Description of problem:
Accidentally introduced when via #1570941 and its associated backports.
$ tox -e pep8
./nova/conf/libvirt.py:27:1: F811 redefinition of unused 'types' from line 25
This isn't required for OSP 11 as this offending change wasn't made there for some reason.