Improve clean of model translation for field that are not more translated for

issue626

trytond/ir/translation.py

@@ -720,13 +720,21 @@ class TranslationClean(Wizard):
                         continue
                 elif translation.type == 'model':
                     try:
-                        model_name, _ = translation.name.split(',', 1)
+                        model_name, field_name = translation.name.split(',', 1)
                     except ValueError:
                         to_delete.append(translation.id)
                         continue
                     if model_name not in self.pool.object_name_list():
                         to_delete.append(translation.id)
                         continue
+                    model_obj = self.pool.get(model_name)
+                    if field_name not in model_obj._columns:
+                        to_delete.append(translation.id)
+                        continue
+                    field = model_obj._columns[field_name]
+                    if not hasattr(field, 'translate') or not field.translate:
+                        to_delete.append(translation.id)
+                        continue
                 elif translation.type == 'odt':
                     if not report_obj.search(cursor, user, [
                         ('report_name', '=', translation.name),