[issue46286] use the new POP_JUMP_IF_NOT_NONE to simplify except* a bit

[Irit Katriel]

Change by Irit Katriel <iritkatriel at gmail.com>:


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keywords: +patch
pull_requests: +28646
stage:  -> patch review
pull_request: https://github.com/python/cpython/pull/30439

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue46286>
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