Attached is a three line diff for
round-0.6.3/roundup/cgi/client.py. Since the content
length is easily available, we should send it. I can't
find it now, but I remember reading somewhere when I
was doing a Java servlet that setting Content-Length
allowed browsers to do things faster.

References:
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.13