Assertion failed with insert into in a collection

[Federico Cavalieri]

The following query crashes zorba
import module namespace ddl = "http://www.zorba-xquery.com/modules/store/dynamic/collections/ddl";
import module namespace dml = "http://www.zorba-xquery.com/modules/store/dynamic/collections/dml";

ddl:create(xs:QName("ddl:test2"),(<center1/>,<oldlast/>));

dml:insert-nodes-first(xs:QName("ddl:test2"), (<c1/>,<c2/>));
dml:collection(xs:QName("ddl:test2"))/self::node()

zorba: /zorba/repository/pul-xdm/src/store/naive/node_items.cpp:345: long int zorba::simplestore::XmlNode::compareInSameTree(const zorba::simplestore::XmlNode*, const zorba::simplestore::XmlNode*) const: Assertion `n1->getTree() == n2->getTree()' faile