fold: sort concatenated commit messages in topological order
It seems better to have the proposed commit message look the same
whether the user ran `hg fold --exact -r . -r .^` or `hg fold --exact
-r .^ -r .`.
This software was downloaded from
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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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