mercurial/node.py

lfs: avoid a potential variable reference before assignment error in cmdserver

A coworker hit this once yesterday when pulling in thg (a retry worked), and
then I hit it with strip after a pull.  I had a difficult time recreating a test
for this (at least one of the tricks was to not use '-R', which seems to cause
reposetup() to be called for each command), so I'm not sure how large of a
window there actually is for this.  Calling reposetup() *after* the requirement
is added will skip the hook entirely.

The other issue I had was adding a couple `ui.status()` lines around the check
that installs the hook.  On Windows, the cmdserver process ballooned to 1.6GB
and hung.  Changing that to `ui.warn()` avoided the hang.  It also hung on
macOS, but without the large memory usage.

# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[e-mail]>
#
# 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

import binascii

# This ugly style has a noticeable effect in manifest parsing
hex = binascii.hexlify
# Adapt to Python 3 API changes. If this ends up showing up in
# profiles, we can use this version only on Python 3, and forward
# binascii.unhexlify like we used to on Python 2.
def bin(s):
    try:
        return binascii.unhexlify(s)
    except binascii.Error as e:
        raise TypeError(e)

nullrev = -1
nullid = b"\0" * 20
nullhex = hex(nullid)

# Phony node value to stand-in for new files in some uses of
# manifests.
newnodeid = '!' * 20
addednodeid = ('0' * 15) + 'added'
modifiednodeid = ('0' * 12) + 'modified'

wdirfilenodeids = {newnodeid, addednodeid, modifiednodeid}

# pseudo identifiers for working directory
# (they are experimental, so don't add too many dependencies on them)
wdirrev = 0x7fffffff
wdirid = b"\xff" * 20
wdirhex = hex(wdirid)

def short(node):
    return hex(node[:6])