Fix broken test from isconstant
Fix broken test from isconstant

aconty/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,lgritz/OpenShadingLanguage,gzorin/OpenShadingLanguage,lgritz/OpenShadingLanguage,gzorin/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,imageworks/OpenShadingLanguage,svenstaro/OpenShadingLanguage,svenstaro/OpenShadingLanguage,brechtvl/OpenShadingLanguage,svenstaro/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,lgritz/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,gzorin/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,imageworks/OpenShadingLanguage,imageworks/OpenShadingLanguage,imageworks/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,brechtvl/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,gzorin/OpenShadingLanguage,brechtvl/OpenShadingLanguage,aconty/OpenShadingLanguage,gzorin/OpenShadingLanguage,lgritz/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,brechtvl/OpenShadingLanguage,lgritz/OpenShadingLanguage,aconty/OpenShadingLanguage,imageworks/OpenShadingLanguage,aconty/OpenShadingLanguage,svenstaro/OpenShadingLanguage