Fix wrong definition of assert
Fix wrong definition of assert

Fix warning error message in unittests log, which was added in patch
Ie881a1bdb88f4bcb1c03c037bcedf2a328d5d41c:

"heat/engine/attributes.py:80: SyntaxWarning: assertion is always true,
perhaps remove parentheses?"

Change-Id: I165d3a1f4e281debd8afb390520f18fc59084b87

noironetworks/heat,srznew/heat,rh-s/heat,cryptickp/heat,srznew/heat,miguelgrinberg/heat,dims/heat,pratikmallya/heat,noironetworks/heat,cryptickp/heat,openstack/heat,takeshineshiro/heat,cwolferh/heat-scratch,maestro-hybrid-cloud/heat,dragorosson/heat,gonzolino/heat,openstack/heat,jasondunsmore/heat,dims/heat,jasondunsmore/heat,pratikmallya/heat,steveb/heat,cwolferh/heat-scratch,steveb/heat,maestro-hybrid-cloud/heat,dragorosson/heat,takeshineshiro/heat,gonzolino/heat,miguelgrinberg/heat,rh-s/heat