[py3] Fixed middleware_exceptions tests.

django/core/handlers/base.py

 from __future__ import unicode_literals
 
 import sys
+import types
 
 from django import http
 from django.core import signals
@@ -125,10 +126,10 @@ class BaseHandler(object):
 
                 # Complain if the view returned None (a common error).
                 if response is None:
-                    try:
-                        view_name = callback.func_name # If it's a function
-                    except AttributeError:
-                        view_name = callback.__class__.__name__ + '.__call__' # If it's a class
+                    if isinstance(callback, types.FunctionType):    # FBV
+                        view_name = callback.__name__
+                    else:                                           # CBV
+                        view_name = callback.__class__.__name__ + '.__call__'
                     raise ValueError("The view %s.%s didn't return an HttpResponse object." % (callback.__module__, view_name))
 
                 # If the response supports deferred rendering, apply template