[py3] Ported django.utils.regex_helper.

django/utils/regex_helper.py

@@ -8,6 +8,7 @@ should be good enough for a large class of URLS, however.
 from __future__ import unicode_literals
 
 from django.utils import six
+from django.utils.six.moves import zip
 
 # Mapping of an escape character to a representative of that class. So, e.g.,
 # "\w" is replaced by "x" in a reverse URL. A value of None means to ignore
@@ -44,8 +45,8 @@ class NonCapture(list):
 
 def normalize(pattern):
     """
-    Given a reg-exp pattern, normalizes it to a list of forms that suffice for
-    reverse matching. This does the following:
+    Given a reg-exp pattern, normalizes it to an iterable of forms that
+    suffice for reverse matching. This does the following:
 
     (1) For any repeating sections, keeps the minimum number of occurrences
         permitted (this means zero for optional groups).
@@ -80,7 +81,7 @@ def normalize(pattern):
     try:
         ch, escaped = next(pattern_iter)
     except StopIteration:
-        return zip([''],  [[]])
+        return [('', [])]
 
     try:
         while True:
@@ -193,9 +194,9 @@ def normalize(pattern):
         pass
     except NotImplementedError:
         # A case of using the disjunctive form. No results for you!
-        return zip([''],  [[]])
+        return [('', [])]
 
-    return zip(*flatten_result(result))
+    return list(zip(*flatten_result(result)))
 
 def next_char(input_iter):
     """