evolve: make fold aware of allowunstable
Before this patch, the fold command was performing the same way regardless of
the value of experimental.evolution.
With this patch if the configuration does not allow unstability, fold won't
create instability.
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'.