Setting sys.tracebacklimit to None is not documented

Documentation

From Misc/NEWS.d/3.6.4rc1:

Fixed several issues in printing tracebacks (PyTraceBack_Print()). Setting sys.tracebacklimit to 0 or less now suppresses printing tracebacks. Setting sys.tracebacklimit to None now causes using the default limit. Setting sys.tracebacklimit to an integer larger than LONG_MAX now means using the limit LONG_MAX rather than the default limit.

That it's possible to set sys.tracebacklimit to None is not documented at https://docs.python.org/3/library/sys.html#sys.tracebacklimit.

Noticed by @tungol in python/typeshed#13173.

Linked PRs

• gh-127556

从 issue 中链接的 Python 文档里的 sys.tracebacklimit 条目开始，并将其与 Misc/NEWS.d/3.6.4rc1 中描述的行为进行比较。记录将 sys.tracebacklimit 设置为 None 会使用默认限制，然后根据链接的 PR gh-127556 核对措辞。