Fix AttributeError with run_validation=true
Fix AttributeError with run_validation=true

This fixes a regression in the recently merged change. [1]

[1] Ie7814bd50f1c57c5f8da8355f665f09c9ac8e2d9

Closes-Bug: #1595823
Change-Id: I135a52f052ed9acebff8e5c2f523a1b08a6fe01e

sebrandon1/tempest,masayukig/tempest,Juniper/tempest,openstack/tempest,vedujoshi/tempest,Tesora/tesora-tempest,cisco-openstack/tempest,Tesora/tesora-tempest,openstack/tempest,cisco-openstack/tempest,sebrandon1/tempest,vedujoshi/tempest,Juniper/tempest,masayukig/tempest