tests/crashgetbundler.py

merge: introduce a clean_update() for that use-case

I find it hard to understand what value to pass for all the arguments
to `merge.update()`. I would like to introduce functions that are more
specific to each use-case. We already have `graft()`. This patch
introduces a `clean_update()` and uses it in some places to show that
it works.

Differential Revision: https://phab.mercurial-scm.org/D7902

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import changegroup, error, extensions


def abort(orig, *args, **kwargs):
    raise error.Abort(_('this is an exercise'))


def uisetup(ui):
    extensions.wrapfunction(changegroup, 'getbundler', abort)