http client: support persistent connections. uses keepalive module from urlgrabber package. tested against "hg serve", cgi server, and through http proxy. used ethereal to verify that only one tcp connection used during entire "hg pull" sequence. if server supports keepalive, this makes latency of "hg pull" much lower.

#!/bin/sh

mkdir test
cd test
echo foo>foo
hg init
hg addremove
hg commit -m 1
hg verify
hg serve -p 20059 -d --pid-file=hg.pid
cd ..

http_proxy= hg clone http://localhost:20059/ copy
cd copy
hg verify
hg co
cat foo
hg manifest
hg pull

kill `cat ../test/hg.pid`