From 092f09fcc184cf611d5a144172c8b49c25c86577 Mon Sep 17 00:00:00 2001
From: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Date: Fri, 27 Jan 2017 00:36:34 +0100
Subject: [PATCH] [1.11.x] Fixed #27781 -- Made simplify_regex() remove
 outstanding '?' characters.

Regression in f0ef0c49e9284f262fbc63e8a497699ca4a248fe.

Backport of c37ec5a6595f963a04fae1b17858225c2b3d08c4 from master
---
 django/contrib/admindocs/views.py | 2 +-
 tests/admin_docs/test_views.py    | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/django/contrib/admindocs/views.py b/django/contrib/admindocs/views.py
index e29f9a3e83..5c6701aef2 100644
--- a/django/contrib/admindocs/views.py
+++ b/django/contrib/admindocs/views.py
@@ -436,7 +436,7 @@ def simplify_regex(pattern):
     pattern = replace_named_groups(pattern)
     pattern = replace_unnamed_groups(pattern)
     # clean up any outstanding regex-y characters.
-    pattern = pattern.replace('^', '').replace('$', '')
+    pattern = pattern.replace('^', '').replace('$', '').replace('?', '')
     if not pattern.startswith('/'):
         pattern = '/' + pattern
     return pattern
diff --git a/tests/admin_docs/test_views.py b/tests/admin_docs/test_views.py
index b48147fc85..bd483007c7 100644
--- a/tests/admin_docs/test_views.py
+++ b/tests/admin_docs/test_views.py
@@ -340,6 +340,7 @@ class AdminDocViewFunctionsTests(SimpleTestCase):
             (r'^(?P<a>(x|y))/b/(?P<c>\w+)$', '/<a>/b/<c>'),
             (r'^(?P<a>(x|y))/b/(?P<c>\w+)ab', '/<a>/b/<c>ab'),
             (r'^(?P<a>(x|y)(\(|\)))/b/(?P<c>\w+)ab', '/<a>/b/<c>ab'),
+            (r'^a/?$', '/a/'),
         )
         for pattern, output in tests:
             self.assertEqual(simplify_regex(pattern), output)