tests/failfilemerge.py

fsmonitor: be robust in the face of bad state

fsmonitor could write out bad state if interrupted part way through, and
would then crash when it tried to read it back in.

Make both sides of the operation more robust - reading state should fail
cleanly, and we can use atomictemp to write out cleanly as the file is
small. Between the two, we shouldn't crash with an IndexError any more.

# 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)