Ensure doesn't use LOG.warn
Ensure doesn't use LOG.warn

This patchs ensure doesn't use LOG.warn because LOG.warn deprecated
in Python 3 [1]. Using LOG.warning should be used instead.

[1] https://docs.python.org/3/library/logging.html#logging.warning

TrivialFix

Change-Id: I464314b33b8d4f31b6be0a765019e1f5668cc6d9

rahulunair/kolla,intel-onp/kolla,stackforge/kolla,mrangana/kolla,coolsvap/kolla,rahulunair/kolla,stackforge/kolla,mandre/kolla,mandre/kolla,dardelean/kolla-ansible,intel-onp/kolla,coolsvap/kolla,nihilifer/kolla,nihilifer/kolla,openstack/kolla,GalenMa/kolla,stackforge/kolla,mrangana/kolla,dardelean/kolla-ansible,coolsvap/kolla,mandre/kolla,GalenMa/kolla,dardelean/kolla-ansible,openstack/kolla