Respect "Connection: close" headers sent by HTTP clients.

A HTTP client can indicate that it doesn't support (or doesn't want)
persistent connections by sending this header.

This not only makes the server more compliant with the RFC, but also
reduces the run time of test-http-proxy when run with python 2.3 from
~125s to ~5s (it doesn't affect it with python 2.4, which was already
~5s).

mercurial/hgweb/server.py

@@ -127,6 +127,11 b' class _hgwebhandler(object, BaseHTTPServ'
             if h[0].lower() == 'content-length':
                 should_close = False
                 self.length = int(h[1])
+        # The value of the Connection header is a list of case-insensitive
+        # tokens separated by commas and optional whitespace.
+        if 'close' in [token.strip().lower() for token in 
+                       self.headers.get('connection', '').split(',')]:
+            should_close = True
         if should_close:
             self.send_header('Connection', 'close')
         self.close_connection = should_close