Imported reduce from functools for forward compatibility.

In Python 3, reduce has to be imported from functools.

django/contrib/admin/views/main.py

@@ -1,4 +1,5 @@
 import operator
+from functools import reduce
 
 from django.core.exceptions import SuspiciousOperation, ImproperlyConfigured
 from django.core.paginator import InvalidPage

django/core/exceptions.py

@@ -1,6 +1,7 @@
 """
 Global Django exception and warning classes.
 """
+from functools import reduce
 
 class DjangoRuntimeWarning(RuntimeWarning):
     pass

django/utils/crypto.py

@@ -8,6 +8,7 @@ import hashlib
 import binascii
 import operator
 import time
+from functools import reduce
 
 # Use the system PRNG if possible
 import random