optimize code for proxy handling of `urllib.request`

Feature or enhancement

Proposal:

1. the second loop of line starts from 1845 is duplicated from the first loop.
   https://github.com/python/cpython/blob/2041a95e68ebf6d13f867e214ada28affa830669/Lib/urllib/request.py#L1817-L1853
2. the registry access should be separated to a standalone function for cache, to be used by code like https://github.com/aio-libs/aiohttp/blob/e79b2d5df70a2644e81925cc49558962af91848d/aiohttp/client.py#L609-L617
   https://github.com/python/cpython/blob/2041a95e68ebf6d13f867e214ada28affa830669/Lib/urllib/request.py#L2071-L2104
3. the proxy setting from registry should be ignored when if proxies from environment exists? like the proxy_bypass()

Should open a PR?

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-127767

Commencez dans Lib/urllib/request.py autour des lignes 1817-1853 et 2071-2104, puis comparez la gestion des proxies de aiohttp liée. Clarifiez si l’objectif inclut la déduplication des boucles, l’extraction de l’accès au registre mis en cache et la priorité donnée aux proxies d’environnement ; le travail est terminé lorsque le comportement des proxies convenu est implémenté et couvert par des tests urllib.request appropriés.