Updated openstack/openstack
Project: openstack/nova  a4b54d4f466536d62cd1d243ca2bbe1c921b115b

Ignore etc/nova/nova.conf.sample

Since we have already remove this sample file, and provided a way
to generate it, it should be no longer tracked.

Change-Id: I786812d039d96044ff5040d09f5472051966f74f
Closes-Bug: #1320150