sparse: move code for importing rules from files into core
This is a pretty straightforward port. Some code cleanup was
performed. But no major changes to the logic were made.
I'm not a huge fan of this function because it does multiple
things. I'd like to get things into core first to facilitate
refactoring later.
Please also note the added inline comment about the oddities
of writeconfig() and the try..except to undo it. This is because
of the hackiness in which the sparse matcher is obtained by
various consumers, notably dirstate. We'll need a massive
refactor to address this. That refactor is effectively blocked
on having the sparse dirstate hacks live in core.
# diffhelpers.py - pure Python implementation of diffhelpers.c
#
# Copyright 2009 Matt Mackall <mpm@selenic.com> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
from ..pure.diffhelpers import *