contrib/tcsh_completion

windows: continue looking at `%HOME%` for user config files with py3.8+

The `%HOME%` variable is explicitly called out in `hg help config` as a location
that is consulted when reading user files, but python stopped looking at it
when expanding '~' in py3.8+.[1]  Restore that old functionality by copying in
the old implementation (and simplifying it to just use bytes).  It could be
simplfied further, since only '~' is passed, but I'm not sure yet if we need to
make this a generic utility function on Windows.  There are other uses of
`os.path.expanduser()`, but this is the only case I know of that documents
`%HOME%` usage.

(The reason for removing it was that it typically isn't set, but it actually is
set in MSYS and PowerShell, and `%HOME%` and `%USERPROFILE%` are different in
MSYS.  I could be convinced to just replace all uses with this as a general
utility, so we don't have to think too hard about BC.)

[1] https://bugs.python.org/issue36264

Differential Revision: https://phab.mercurial-scm.org/D9559

#
# tcsh completion for Mercurial
#
# This file has been auto-generated by tcsh_completion_build.sh for
# Mercurial Distributed SCM (version 1.7.5+157-8a220ae0b2ba)
#
# Copyright (C) 2005 TK Soh.
#
# This is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#

complete hg \
  'n/--cwd/d/' 'n/-R/d/' 'n/--repository/d/' \
  'C/-/( -R --repository \
    --cwd \
    -y --noninteractive \
    -q --quiet \
    -v --verbose \
    --config \
    --debug \
    --debugger \
    --encoding \
    --encodingmode \
    --traceback \
    --time \
    --profile \
    --version \
    -h --help)/' \
  'p/1/(add addremove annotate blame archive \
    backout bisect bookmarks branch branches \
    bundle cat clone commit ci \
    copy cp debugancestor debugbuilddag debugcheckstate \
    debugcommands debugcomplete debugdag debugdata debugdate \
    debugfsinfo debugignore debugindex debugindexdot debuginstall \
    debugpushkey debugrebuildstate debugrename debugrevspec debugsetparents \
    debugstate debugsub debugwalk diff export \
    forget grep heads help identify \
    id import patch incoming in \
    init locate log history manifest \
    merge outgoing out parents paths \
    pull push recover remove rm \
    rename move mv resolve revert \
    rollback root serve showconfig debugconfig \
    status st summary sum tag \
    tags tip unbundle update up \
    checkout co verify version)/'