[1.0.X] Revised r9567 slightly to be backwards compatible with versions 1.0 - 1.0.2.

Also documented the change. We prefer to load directory_index.html for static
directory listings, but if you have the (older style) "directory_index"
template and no .html version, we'll load that. This should stop a bunch of
mysterious breakages when people upgrade to Django 1.0.3 or Django 1.1. Also
keeps the docs in sync with released code.

Fixed #9993.

Backport of r9725 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@9726 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/howto/static-files.txt

@@ -90,7 +90,7 @@ You can customize the index view by creating a template called
     * ``directory`` -- the directory name (a string)
     * ``file_list`` -- a list of file names (as strings) in the directory
 
-Here's the default ``static/directory_index`` template:
+Here's the default ``static/directory_index.html`` template:
 
 .. code-block:: html+django
 
@@ -112,6 +112,14 @@ Here's the default ``static/directory_index`` template:
     </body>
     </html>
 
+.. versionchanged:: 1.0.3
+    Prior to Django 1.0.3, there was a bug in the view that provided directory
+    listings. The template that was loaded had to be called
+    ``static/directory_listing`` (with no ``.html`` extension). For backwards
+    compatibility with earlier versions, Django will still load templates with
+    the older (no extension) name, but it will prefer a the
+    ``directory_index.html`` version.
+
 Limiting use to DEBUG=True
 ==========================