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，使用針對 pypi.org URL 的 Request 重現 urllib.request.urlopen 呼叫，並比較 timeout=30 與 timeout=1。閱讀相關 issue #95838，調查要求在哪個環節停止回應；當長時間掛起得到解釋，且回報的行為已修正或明確縮小範圍時，即視為完成。