Updated openstack/openstack
Project: openstack/oslo.rootwrap  c651d837a716dfbbb68fb44d5789e9c4384a0bd1

Activate pep8 check that _ is imported

Currently translatable messages are not used, so there are no uses
of _.

This will ensure if _ is used in the future pep8 won't assume
it is provided as a builtin.

Change-Id: Ifd514de79f8c82bb2423d9e7e7f8479f16d5f71c