Fixed #16904 -- Additional clarification regarding contrib.messages iteration.…

Fixed #16904 -- Additional clarification regarding contrib.messages iteration. Thanks murphyke for the report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16866 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/ref/contrib/messages.txt

@@ -183,6 +183,10 @@ If you're using the context processor, your template should be rendered with a
 ``RequestContext``. Otherwise, ensure ``messages`` is available to
 the template context.
 
+Even if you know there is only just one message, you should still iterate over
+the ``messages`` sequence, because otherwise the message storage will not be cleared
+for the next request.
+
 Creating custom message levels
 ------------------------------