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'.

abort: Connection refused
255
copy: No such file or directory
changeset:   0:53e17d176ae6
tag:         tip
user:        test
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     test

requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
foo
pulling from static-http://localhost:20059/remote
searching for changes
no changes found