tests/failfilemerge.py

lfs: avoid quadratic performance in processing server responses

This is also adapted from the Facebook repo[1].  Unlike there, we were already
reading the download stream in chunks and immediately writing it to disk, so we
basically avoided the problem on download.  There shouldn't be a lot of data to
read on upload, but it's better to get rid of this pattern.

[1] https://github.com/facebookexperimental/eden/commit/82df66ffe97e21f3ee73dfec093c87500fc1f6a7

Differential Revision: https://phab.mercurial-scm.org/D7882

# 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("^C")
    return filemergefn(premerge, repo, mynode, orig, fcd, fco, fca, labels)


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