Always skip id in _get_on_change_values

issue8234

proteus/__init__.py

@@ -973,8 +973,10 @@ class Model(object):
         else:
             definitions = self._fields.items()
         for field, definition in definitions:
+            if field == 'id':
+                continue
             if not fields:
-                if field == 'id' or (skip and field in skip):
+                if skip and field in skip:
                     continue
                 if (self.id >= 0
                         and (field not in self._values