http server: support persistent connections. only "hg serve" affected yet. http server running cgi script will not use persistent connections. support for fastcgi will help that. clients that support keepalive can use one tcp connection for all commands during clone and pull. this makes latency of binary search during pull much lower over wan. if server does not know content-length, it will force connection to close at end. right fix is to use chunked transfer-encoding but this is easier and does not hurt performance. only command that is affected is "changegroup" which is always last command during a pull.

#!/bin/sh

hg init a
cd a
echo a > foo
hg rm foo
hg add foo
hg commit -m 1 -d "1000000 0"
hg remove
rm foo
hg remove foo
hg revert
rm foo
hg remove --after
hg commit -m 2 -d "1000000 0"
hg export 0
hg export 1
hg log -p -r 0
hg log -p -r 1

echo a > a
hg add a
hg rm a
hg rm -f a
echo b > b
hg ci -A -m 3 -d "1000001 0"
echo c >> b
hg rm b
hg rm -f b

cd ..
hg clone a b