trivial: Mock warnings
trivial: Mock warnings

These were being spewed by zuul.

Change-Id: Ifaf41d074d0b43a64c414a1d21cf17c3bbc9f2fa
Signed-off-by: Stephen Finucane <4725dc7f3632bf126d9fbdc30c347e91e8d2fe16@redhat.com>

openstack/oslo.versionedobjects