Index: django/core/urlresolvers.py
===================================================================
--- django/core/urlresolvers.py	(revision 8389)
+++ django/core/urlresolvers.py	(working copy)
@@ -92,8 +92,9 @@
     Raises NoReverseMatch if the args/kwargs aren't valid for the regex.
     """
     # TODO: Handle nested parenthesis in the following regex.
-    result = re.sub(r'\(([^)]+)\)', MatchChecker(args, kwargs), regex.pattern)
-    return result.replace('^', '').replace('$', '').replace('\\', '')
+    pattern = re.sub(r'\(\?[iLmsux]+\)','',regex.pattern)
+    result = re.sub(r'\(([^)]+)\)', MatchChecker(args, kwargs), pattern)
+    return result.replace('^', '').replace('$', '').replace('?','')
 
 class MatchChecker(object):
     "Class used in reverse RegexURLPattern lookup."