extend network protocol to stop clients from locking servers now all repositories have capabilities slot, tuple with list of names. if 'unbundle' capability present, repo supports push where client does not need to lock server. repository classes that have unbundle capability also have unbundle method. implemented for ssh now, will be base for push over http. unbundle protocol acts this way. server tells client what heads it has during normal negotiate step. client starts unbundle by repeat server's heads back to it. if server has new heads, abort immediately. otherwise, transfer changes to server. once data transferred, server locks and checks heads again. if heads same, changes can be added. else someone else added heads, and server aborts. if client wants to force server to add heads, sends special heads list of 'force'.

#!/bin/sh

hg init
echo a > a
hg add a
hg commit -m "1" -d "1000000 0"
hg status
hg copy a b
hg status
hg --debug commit -m "2" -d "1000000 0"
echo "we should see two history entries"
hg history -v
echo "we should see one log entry for a"
hg log a
echo "this should show a revision linked to changeset 0"
hg debugindex .hg/data/a.i
echo "we should see one log entry for b"
hg log b
echo "this should show a revision linked to changeset 1"
hg debugindex .hg/data/b.i

echo "this should show the rename information in the metadata"
hg debugdata .hg/data/b.d 0 | head -3 | tail -2

$TESTDIR/md5sum.py .hg/data/b.i
hg cat b > bsum
$TESTDIR/md5sum.py bsum
hg cat a > asum
$TESTDIR/md5sum.py asum
hg verify