evolve: allow updating to the successor if the parent is obsolete
Although 'hg update' handles this as well, it will also update to
tipmost descendent of the successor, if any.
This software was downloaded from
https://bitbucket.org/marmoute/mutable-history
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'.