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argparse: Unexpanded replacements in "unknown action" exception #134970

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argparse: Unexpanded replacements in "unknown action" exception#134970
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3.14bugs and security fixes3.15new features, bugs and security fixesstdlibStandard Library Python modules in the Lib/ directorytype-bugAn unexpected behavior, bug, or error
@mgorny

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@mgorny
mgorny
opened on May 31, 2025

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Bug description:

cpython/Lib/argparse.py

Lines 1536 to 1537 in ad39f01

if not callable(action_class):
raise ValueError('unknown action {action_class!r}')

There is a missing f there, so the replacements don't happen. Noticed accidentally because it broke snakeoil's test suite.

CPython versions tested on:

3.14, CPython main branch

Operating systems tested on:

Linux

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    3.14bugs and security fixes3.15new features, bugs and security fixesstdlibStandard Library Python modules in the Lib/ directorytype-bugAn unexpected behavior, bug, or error

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