[py3] Removed a remaining use of __metaclass__.

django/db/models/fields/subclassing.py

@@ -2,8 +2,9 @@
 Convenience routines for creating non-trivial Field subclasses, as well as
 backwards compatibility utilities.
 
-Add SubfieldBase as the __metaclass__ for your Field subclass, implement
-to_python() and the other necessary methods and everything will work seamlessly.
+Add SubfieldBase as the metaclass for your Field subclass, implement
+to_python() and the other necessary methods and everything will work
+seamlessly.
 """
 
 class SubfieldBase(type):

django/forms/models.py

@@ -401,13 +401,8 @@ def modelform_factory(model, form=ModelForm, fields=None, exclude=None,
         'formfield_callback': formfield_callback
     }
 
-    form_metaclass = ModelFormMetaclass
-
-    # TODO: this doesn't work under Python 3.
-    if issubclass(form, BaseModelForm) and hasattr(form, '__metaclass__'):
-        form_metaclass = form.__metaclass__
-
-    return form_metaclass(class_name, (form,), form_class_attrs)
+    # Instatiate type(form) in order to use the same metaclass as form.
+    return type(form)(class_name, (form,), form_class_attrs)
 
 
 # ModelFormSets ##############################################################