closer behaviour from the UI for getting an effective model in a composition

product/ERP5/mixin/composition.py

@@ -80,6 +80,11 @@ def _getEffectiveModel(self, start_date, stop_date):
        return self
     raise KeyError('No %s found with the reference %s between %s and %s' % \
             (self.getPortalType(), reference, start_date, stop_date))
+  # After a clone, we can have 2 models with same start_date, stop_date, and
+  # version. We want to compose with the model explicitely defined in the relation field
+  if len(model_list) > 1 and \
+    model_list[0].getVersion() == model_list[1].getVersion():
+    return self
   return model_list[0].getObject()