urllib.request.urlopen hangs for multiple minutes with timeout=30 and works with timeout=1

Bug report

Bug description:

import urllib.request
urllib.request.urlopen(urllib.request.Request("https://pypi.org/pypi/MozPhab/json"), timeout=30)

Somehow this hangs, and Control+C doesn't stop it. The same URL loads instantly on Firefox and Node.js. Any help to investigate this further will be appreciated. (Could be related to #95838, except I don't have any VPN on this machine.)

Coming from https://bugzilla.mozilla.org/show_bug.cgi?id=1919884.

CPython versions tested on:

3.12

Operating systems tested on:

Windows

首先，在使用 Python 3.12 的 Windows 上，使用针对 pypi.org URL 的 Request 重现 urllib.request.urlopen 调用，并比较 timeout=30 与 timeout=1。阅读相关 issue #95838，调查请求在哪个环节停止响应；当长时间挂起得到解释，并且报告的行为已修复或明确缩小范围时，即视为完成。