Because this call specifies AUC ('true') and Gini ('true') and omits the ROC argument, the ROC argument has the value 'false'.
SELECT * FROM ROC ( ON (SELECT 1) PARTITION BY 1 InputTable ('iris') ProbabilityColumn ('prob2') ObsColumn ('obs') OutputTable ('irisout18') PositiveClass ('2') NumThreshold ('100') AUC ('true') Gini ('true') );