[MERGE] Add function to find the root of a checkout branch

I've pushed one more revision to
https://code.launchpad.net/~bojan-bnikolic/dvc/dev, this one is useful
for when working with checkouts of local branches. 

------------------------------------------------------------
revno: 440
committer: Bojan Nikolic <b.nikolic <at> mrao.cam.ac.uk>
branch nick: nikolic
timestamp: Mon 2009-06-08 19:02:53 +0100
message:
  Add function to find the root of a checkout branch

# Bazaar merge directive format 2 (Bazaar 0.90)
# revision_id: b.nikolic <at> mrao.cam.ac.uk-20090608180253-\
#   qwt90wi5h4y0v9dz
# target_branch: http://bzr.xsteve.at/dvc/
# testament_sha1: 4229034734537de40109f625c03e35bdc76e1764
# timestamp: 2009-06-09 07:24:48 +0100
# source_branch: ../main/
# base_revision_id: stefan <at> xsteve.at-20090603174201-fk7gnb07dabchcn7
# 
# Begin patch
=== modified file 'lisp/bzr.el'
--- lisp/bzr.el	2009-03-15 14:09:56 +0000
+++ lisp/bzr.el	2009-06-08 18:02:53 +0000
@@ -156,7 +156,11 @@
 (defun bzr-push (&optional repo-path)