Fixed #16935 - misleading message if AttributeError escapes during SimpleTemplateResponse.render

Thanks to isagalaev for the report.

As discussed on django-devs, this reverts some of the changes in [16568]
i.e.  the addition of `SimpleTemplateResponse.__getattr__`, because this
makes it much harder to debug the common case of an AttributeError somewhere
during the rendering of a SimpleTemplateResponse.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16917 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/template/response.py

@@ -6,10 +6,6 @@ class ContentNotRenderedError(Exception):
     pass
 
 
-class DiscardedAttributeError(AttributeError):
-    pass
-
-
 class SimpleTemplateResponse(HttpResponse):
     rendering_attrs = ['template_name', 'context_data', '_post_render_callbacks']
 
@@ -36,7 +32,6 @@ class SimpleTemplateResponse(HttpResponse):
         # True, so we initialize it to False after the call to super __init__.
         self._is_rendered = False
 
-
     def __getstate__(self):
         """Pickling support function.
 
@@ -54,13 +49,6 @@ class SimpleTemplateResponse(HttpResponse):
 
         return obj_dict
 
-    def __getattr__(self, name):
-        if name in self.rendering_attrs:
-            raise DiscardedAttributeError('The %s attribute was discarded '
-                                          'when this %s class was pickled.' %
-                                          (name, self.__class__.__name__))
-        return super(SimpleTemplateResponse, self).__getattr__(name)
-
     def resolve_template(self, template):
         "Accepts a template object, path-to-template or list of paths"
         if isinstance(template, (list, tuple)):