From 9390da7fb6e251eaa9a785692f987296cb14523f Mon Sep 17 00:00:00 2001
From: ieatkittens <samuelm@gadventures.com>
Date: Fri, 18 Mar 2016 15:21:41 -0400
Subject: [PATCH] Fixed #26293 -- Fixed CommonMiddleware to process PREPEND_WWW
 and APPEND_SLASH independently.

---
 django/middleware/common.py | 21 +++++++++++----------
 docs/releases/1.9.5.txt     |  3 +++
 tests/middleware/tests.py   |  7 +------
 3 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/django/middleware/common.py b/django/middleware/common.py
index 70d8c57f7e..2135702062 100644
--- a/django/middleware/common.py
+++ b/django/middleware/common.py
@@ -54,18 +54,19 @@ class CommonMiddleware(object):
 
         # Check for a redirect based on settings.PREPEND_WWW
         host = request.get_host()
+        must_prepend = settings.PREPEND_WWW and host and not host.startswith('www.')
+        redirect_url = ('%s://www.%s' % (request.scheme, host)) if must_prepend else ''
 
-        if settings.PREPEND_WWW and host and not host.startswith('www.'):
-            host = 'www.' + host
+        # Check if a slash should be appended
+        if self.should_redirect_with_slash(request):
+            path = self.get_full_path_with_slash(request)
+        else:
+            path = request.get_full_path()
 
-            # Check if we also need to append a slash so we can do it all
-            # with a single redirect.
-            if self.should_redirect_with_slash(request):
-                path = self.get_full_path_with_slash(request)
-            else:
-                path = request.get_full_path()
-
-            return self.response_redirect_class('%s://%s%s' % (request.scheme, host, path))
+        # Return a redirect if necessary
+        if redirect_url or path != request.get_full_path():
+            redirect_url += path
+            return self.response_redirect_class(redirect_url)
 
     def should_redirect_with_slash(self, request):
         """
diff --git a/docs/releases/1.9.5.txt b/docs/releases/1.9.5.txt
index 37157b3e56..c88e92031f 100644
--- a/docs/releases/1.9.5.txt
+++ b/docs/releases/1.9.5.txt
@@ -34,3 +34,6 @@ Bugfixes
 * Fixed a crash when using a reverse lookup with a subquery when a
   ``ForeignKey`` has a ``to_field`` set to something other than the primary key
   (:ticket:`26373`).
+
+* Fixed a regression in ``CommonMiddleware`` that caused spurious warnings in
+  logs on requests missing a trailing slash (:ticket:`26293`).
diff --git a/tests/middleware/tests.py b/tests/middleware/tests.py
index dd26d68056..d0e4cf349e 100644
--- a/tests/middleware/tests.py
+++ b/tests/middleware/tests.py
@@ -67,10 +67,8 @@ class CommonMiddlewareTest(SimpleTestCase):
         APPEND_SLASH should redirect slashless URLs to a valid pattern.
         """
         request = self.rf.get('/slash')
-        response = HttpResponseNotFound()
-        r = CommonMiddleware().process_response(request, response)
+        r = CommonMiddleware().process_request(request)
         self.assertEqual(r.status_code, 301)
-        self.assertEqual(r.url, '/slash/')
 
     @override_settings(APPEND_SLASH=True)
     def test_append_slash_redirect_querystring(self):
@@ -301,9 +299,6 @@ class CommonMiddlewareTest(SimpleTestCase):
         request = self.rf.get('/slash')
         request.META['QUERY_STRING'] = force_str('drink=café')
         r = CommonMiddleware().process_request(request)
-        self.assertIsNone(r)
-        response = HttpResponseNotFound()
-        r = CommonMiddleware().process_response(request, response)
         self.assertEqual(r.status_code, 301)
 
     def test_response_redirect_class(self):