Fix crash in "make html" introduced by the global env
Fix crash in "make html" introduced by the global env

Change-Id: Iece0e122841829d3561b71575065ffa7b656b504

steveb/heat,miguelgrinberg/heat,openstack/heat,NeCTAR-RC/heat,takeshineshiro/heat,cryptickp/heat,varunarya10/heat,cryptickp/heat,gonzolino/heat,citrix-openstack-build/heat,varunarya10/heat,NeCTAR-RC/heat,dragorosson/heat,rdo-management/heat,srznew/heat,pratikmallya/heat,maestro-hybrid-cloud/heat,cwolferh/heat-scratch,rh-s/heat,gonzolino/heat,cwolferh/heat-scratch,rh-s/heat,rickerc/heat_audit,rickerc/heat_audit,citrix-openstack-build/heat,rdo-management/heat,redhat-openstack/heat,ntt-sic/heat,pshchelo/heat,miguelgrinberg/heat,steveb/heat,maestro-hybrid-cloud/heat,pratikmallya/heat,pshchelo/heat,redhat-openstack/heat,jasondunsmore/heat,noironetworks/heat,dims/heat,openstack/heat,srznew/heat,ntt-sic/heat,takeshineshiro/heat,dims/heat,jasondunsmore/heat,noironetworks/heat,JioCloud/heat,dragorosson/heat,JioCloud/heat