config: have a way to backup and restore value in config
This is introduce to allow temporary overwriting of a config value while being
able to reinstall the old value once done. The main advantage over using
``config`` and ``setconfig`` is that backup and restore will properly restore
the lack of any config. Restoring the fact that there was no value is important
to allow config user to keep using meaniful default value.
A more naive approach will result in the following scenario::
Before:
config(section, item, my_default) --> my_default
temporal overwrite
old = config(section, item)
…
setconfig(section, item, old)
After
config(section, item, my_default) --> None
The first user of this feature should be mq to overwriting minimal phase of
future commit.
# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import binascii
nullrev = -1
nullid = "\0" * 20
# This ugly style has a noticeable effect in manifest parsing
hex = binascii.hexlify
bin = binascii.unhexlify
def short(node):
return hex(node[:6])