title: Django, csrf_token does not appear on form after redirection
body: <p>I am using this middleware to redirect all pages to a landing page: (part of <code>AuthRequiredMiddleware</code> class.</p>
  
  <pre><code>def process_request(self, request):
      assert hasattr(request, 'user') 
      if not request.user.is_authenticated():
          path = request.path_info.lstrip('/')
          if path not in ['ipn/', 'pp_cancel/', 'pp_success/', 'sitemap/', 'welcome/']:
              lang = request.GET.get('lang', 'en')
              ru = request.GET.get('ru', '')
              return render_to_response('landing_en.html', RequestContext(request, {'ru': ru}))
  </code></pre>
  
  <p>and this is my <code>settings.py</code></p>
  
  <pre><code>MIDDLEWARE_CLASSES = (                                                                                                                                                                                   
       'django.middleware.cache.UpdateCacheMiddleware',
       'django.contrib.sessions.middleware.SessionMiddleware',
       'django.middleware.locale.LocaleMiddleware',
       'main.common.SessionBasedLocaleMiddleware.SessionBasedLocaleMiddleware',
       'django.middleware.common.CommonMiddleware',
       'django.middleware.cache.FetchFromCacheMiddleware',
       'django.middleware.csrf.CsrfViewMiddleware',
       'django.contrib.auth.middleware.AuthenticationMiddleware',
       'django.contrib.messages.middleware.MessageMiddleware',
       'main.common.tz_middleware.TimezoneMiddleware',
       'main.common.sslMiddleware.SSLRedirect',
       'main.common.RedirectAllMiddleware.AuthRequiredMiddleware',
  )
  </code></pre>
  
  <p>if the url is (for example) <code>/welcome/</code> and no redirection is performed <code>{% csrf_token %}</code> works and shows in the form. If user is redirected no csrf_token is shown in the form. </p>
  
  <p>What am I doing wrong?</p>