fix regression in handling of undef values
fix regression in handling of undef values

nunoplopes/alive,rutgers-apl/alive-loops,chubbymaggie/alive,chubbymaggie/alive,nunoplopes/alive,nunoplopes/alive,rutgers-apl/alive-loops,davemenendez/alive,chubbymaggie/alive,nunoplopes/alive,rutgers-apl/alive-loops,davemenendez/alive,rutgers-apl/alive-loops,chubbymaggie/alive