compare entities and parent/property lists

redo !155 (diffs)

unittests/test_apiutils.py

@@ -569,6 +569,16 @@ B: something else"""
     assert recB.get_property("propA").unit == "cm"
 
 
+
+    # test whether an id is correctly overwritten by an entity without id
+    recA = db.Record().add_parent("A").add_property(name="B", value=112)
+    newRec = db.Record()
+    recB = db.Record().add_parent("A").add_property(name="B", value=newRec)
+
+    merge_entities(recA, recB, force=True)
+    assert recA.get_property("B").value == newRec
+
+
 def test_merge_missing_list_datatype_82():
     """Merging two properties, where the list-valued one has no datatype."""