evolve: fix content-divergence resolution when p1 is null (issue6201)
Before this fix, in cases like in the added test, the revision number -1 of the
parent was misinterpreted to mean the tipmost revision instead of the null
revision, causing the content-divergence resolution to fail.
This software was downloaded from
https://www.mercurial-scm.org/repo/evolve/
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>
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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'.