demandimport: don't delay threading import
A recent cpython change breaks demandimport by importing threading
locally in importlib.util.LazyLoader.exec_module; add it (plus warnings
and _weakrefset, which are imported by threading) to demandimport's
ignore list.
```
Traceback (most recent call last):
File "/usr/bin/hg", line 57, in <module>
from mercurial import dispatch
File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
File "/usr/lib/python3/dist-packages/hgdemandimport/demandimportpy3.py", line 52, in exec_module
super().exec_module(module)
File "<frozen importlib.util>", line 257, in exec_module
File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
File "/usr/lib/python3/dist-packages/hgdemandimport/demandimportpy3.py", line 52, in exec_module
super().exec_module(module)
File "<frozen importlib.util>", line 267, in exec_module
AttributeError: partially initialized module 'threading' has no attribute 'RLock' (most likely due to a circular import)
```
Ref: https://github.com/python/cpython/issues/117983
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1076449
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1076747
#
# 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)/'