evolve: lock the working copy early in next and prev (issue5244)
Both next and prev depend on a consistent working copy, but were waiting to
take the lock until they were ready to alter the working copy.
Take the lock before reading the working copy state, and do not release it
until we're definitely not going to change the working copy.
This software was downloaded from
http://hg.netv6.net/evolve-main/
Copyright 2011 Peter Arrenbrecht <peter.arrenbrecht@gmail.com>
Logilab SA <contact@logilab.fr>
Pierre-Yves David <pierre-yves.david@ens-lyon.org>
Patrick Mezard <patrick@mezard.eu>
This software may be used and distributed according to the terms of the GNU
General Public License version 2 or any later version.
On Debian systems, the complete text of the GNU General Public License version
2 can be found in `/usr/share/common-licenses/GPL-2'.