title: python requests does not POST after redirect
body: <p>For some reason python requests does not do rePOST after encountered redirect header</p>
  
  <pre><code>import requests
  
  proxies = {'http': 'http://127.0.0.1:8888',}
      headers = {
          'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.87 Safari/537.36',
          'content-type': 'application/x-www-form-urlencoded'}
  
      r = requests.post(url, data, headers=headers, timeout=timeout, proxies=proxies, allow_redirects=True,)
      html = r.text
  </code></pre>
  
  <p>So it means I can't login to any form that is behind redirect. How can I solve this issue? Thank you!</p>