Server crashes after select xmlisvalid (validate_prepare/base)

SELECT XMLISVALID('<root>x</root>','<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:complexType name="A"><xs:simpleContent><xs:extension base="B"/></xs:simpleContent></xs:complexType><xs:complexType name="B"><xs:simpleContent><xs:extension base="A"/></xs:simpleContent></xs:complexType><xs:element name="root" type="A"/></xs:schema>') AS r;