Use field.set to set value from on_change calls

Setting a reference field with an on_change in an editable list won't set the
correct value for the model selection. We should do like in tryton and call
set.

issue9083
review297071003

src/model.js

@@ -1490,7 +1490,7 @@
             record._changed[this.name] = true;
         },
         set_on_change: function(record, value) {
-            record._values[this.name] = value;
+            this.set(record, value);
             record._changed[this.name] = true;
         },
         changed: function(record) {