tests/failfilemerge.py

dirstate-v2: fix infinite loop in pure packer

Due to the naive approach to path relative-ness, some tree shapes
like the one introduced in the associated test could result in the
packer going into an endless loop which allocated new `Node` objects
endlessly until the process was killed by Linux's OOM killer.

Differential Revision: https://phab.mercurial-scm.org/D12170

# extension to emulate interrupting filemerge._filemerge

from __future__ import absolute_import

from mercurial import (
    error,
    extensions,
    filemerge,
)


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


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