title: UnknownTimeZoneError when using RequestContext
body: <p>When using Django 1.4, I am getting an <code>UnknownTimeZoneError</code> for <code>America/Chicago</code> when using RequestContext, but it works without it...any ideas?</p>
  
  <p><b>Error Message</b></p>
  
  <pre><code>UnknownTimeZoneError at /my_proj/bad_view/
  'America/Chicago'
  </code></pre>
  
  <p><b>Source</b></p>
  
  <pre><code># This works
  def good_view(request):
      data = {}
      return render_to_response('mytemplate.html',
                                data)
  
  # This doesn't
  def bad_view(request):
      data = {}
      return render_to_response('mytemplate.html',
                                data,
                                context_instance=RequestContext(request))
  </code></pre>