title: Python requests remove Connection header
body: <p>I'm currently needing to make a single HTTP request to a bunch of servers that I have in a list however, these HTTP requests contain a 'Connection' header, which I need to remove.  How would I do this?</p>
  
  <p>I had the same issue with Accept-Encoding, but I was able to comment out the section that automatically applies that header in httpclient.py (I'm using the requests lib for this).  Is there any way around this aside from using sockets and sending raw HTTP requests?  Is there maybe another snippet that can be commented out to prevent the header from being automatically added?</p>
  
  <p>I realize that removing the header is a bad idea in the real world, but there's justification for this and it 100% needs to be removed.</p>
  
  <p>I've tried assign it as empty and NoneType, both appear to be failing.  I'm wondering if this is something I can't change.</p>