[issue40300] logging.Formatter crashes when default_msec_format is None.

[Mariusz Felisiak]

Change by Mariusz Felisiak <felisiak.mariusz at gmail.com>:


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keywords: +patch
pull_requests: +18897
stage:  -> patch review
pull_request: https://github.com/python/cpython/pull/19551

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40300>
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