[issue31786] In select.poll.poll() ms can be 0 if timeout < 0

[Pablo Galindo Salgado]

Change by Pablo Galindo Salgado <pablogsal at gmail.com>:


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pull_requests: +3997
stage: backport needed -> patch review

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue31786>
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