title: ContentNotRenderedError after a django upgrade
body: <p>Here's a middleware that I use:</p>
  
  <pre><code>class StatsMiddleware(object):
      def process_view(self, request, view_func, view_args, view_kwargs):
          # get number of db queries before we do anything
          n = len(connection.queries)
  
          # time the view
          start = time.time()
          response = view_func(request, *view_args, **view_kwargs)
          totTime = time.time() - start
  
          # compute the db time for the queries just run
          queries = len(connection.queries) - n
          if queries:
          dbTime = reduce(add, [float(q['time']) 
                                for q in connection.queries[n:]])
          else:
              dbTime = 0.0
  
          # and backout python time
          pyTime = totTime - dbTime
  
          stats = {
          'totTime': totTime,
          'pyTime': pyTime,
          'dbTime': dbTime,
          'queries': queries,
          'sql': '&lt;br /&gt;'.join([ '&lt;div class="stats_sql_query"&gt;%s&lt;/div&gt;&lt;div class="stats_sql_time"&gt;%s s&lt;/div&gt;' % (q['sql'], q['time']) for q in connection.queries[n:]]),
          }
  
          # clean query cache
          db.reset_queries()
  
          # replace the comment if found            
          if response and response.content:
              s = response.content
              regexp = re.compile(r'(?P&lt;cmt&gt;&lt;!--\s*STATS:(?P&lt;fmt&gt;.*?)--&gt;)')
              match = regexp.search(s)
              if match:
                  s = s[:match.start('cmt')] + \
                      match.group('fmt') % stats + \
                      s[match.end('cmt'):]
                  response.content = s
  
          return response
  </code></pre>
  
  <p>It has been working perfectly for me up to django 1.3 but this broke when I upgraded to django trunk (1.4+) today, with the exception:-</p>
  
  <pre><code>Traceback:
  File "./../django-trunk/django/core/handlers/base.py" in get_response
    105.                         response = middleware_method(request, callback, callback_args, callback_kwargs)
  File "misc/middleware.py" in process_view
    63.         if response and response.content:
  File "./../django-trunk/django/template/response.py" in _get_content
    123.             raise ContentNotRenderedError('The response content must be '
  
  Exception Type: ContentNotRenderedError at /
  Exception Value: The response content must be rendered before it can be accessed.
  </code></pre>
  
  <p>Would appreciate it if some one using django trunk points me in the right direction. Thanks!</p>