TST: make one property a list property

tests/test_select.py

@@ -68,7 +68,7 @@ def setup_module():
     house.description = "A rather large house"
     house.add_parent("TestHouse")
     house.add_property(rt_person, name="TestOwner", value=owner)
-    house.add_property("TestWindow", window)
+    house.add_property("TestWindow", [window], datatype=db.LIST("TestWindow"))
     house.add_property("TestDoor", door)
     house.insert()