Report on push/pull if heads are merged, too, like for new heads. Use case: If a remote repo has two heads and I _want_ to merge them, I merge and push. Meanwhile someone else pushed on top of one of the heads. He won't get a warning, because he doesn't create a new head, I won't notice that I don't close a head, because I don't get a message telling me.

# repo.py - repository base classes for mercurial
#
# Copyright 2005 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

class RepoError(Exception): pass