rewriteutil: allow rewriting merge commits (issue4561) This patch simply allows rewriteutil.rewrite() to work with commits with multiple parents (i.e. merges). That function is used in such commands as fold, metaedit, touch, rewind. The issue 4561 is marked as easy, the limitation is called unnecessary, no tests fail after this change. What can go wrong.

# Copyright 2019 Pierre-Yves David <pierre-yves.david@octobus.net>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

def hastopicext(repo):
    """True if the repo use the topic extension"""
    return getattr(repo, 'hastopicext', False)