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