title: python: httplib error: can not send headers
body: <pre><code>conn = httplib.HTTPConnection('thesite')
  conn.request("GET","myurl")
  conn.putheader('Connection','Keep-Alive')
  #conn.putheader('User-Agent','Mozilla/5.0(Windows; u; windows NT 6.1;en-US) AppleWebKit/533.4 (KHTML, like Gecko) Chrome//5.0.375.126 Safari//5.33.4')
  #conn.putheader('Accept-Encoding','gzip,deflate,sdch')
  #conn.putheader('Accept-Language','en-US,en;q=0.8')
  #conn.putheader('Accept-Charset','ISO-8859-1,utf-8;1=0.7,*;q=0.3')
  conn.endheaders()
  r1= conn.getresponse()
  </code></pre>
  
  <p>It raises an error:</p>
  
  <pre><code>  conn.putheader('Connection','Keep-Alive')
    File "D:\Program Files\python\lib\httplib.py", line 891, in putheader
      raise CannotSendHeader()
  </code></pre>
  
  <p>If I comment out <code>putheader</code> and <code>endheaders</code>, it runs fine. But I need it to be keep alive.</p>
  
  <p>Does anyone know what I did wrong?</p>