tests/failfilemerge.py

changegroup: replace getlocalchangegroupraw with makestream

As part of reducing the number of changegroup creation apis, let's replace calls
to getlocalchangegroupraw with calls to makestream. Aside from one case of
checking if there are no outgoing commits and returning None, this is pretty
much a drop in replacement.

Differential Revision: https://phab.mercurial-scm.org/D666

# extension to emulate interrupting filemerge._filemerge

from __future__ import absolute_import

from mercurial import (
    error,
    extensions,
    filemerge,
)

def failfilemerge(filemergefn,
                  premerge, repo, mynode, orig, fcd, fco, fca, labels=None):
    raise error.Abort("^C")
    return filemergefn(premerge, repo, mynode, orig, fcd, fco, fca, labels)

def extsetup(ui):
    extensions.wrapfunction(filemerge, '_filemerge',
                            failfilemerge)