tests/failfilemerge.py

engine: prevent multiple checking of re-delta-multibase

The _perform_clone function is called for each revlog cloned, hence we should
prevent this function call overhead.

Differential Revision: https://phab.mercurial-scm.org/D9669

# 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)