`SSL_CERT_FILE` and `SSL_CERT_DIR` environment variables are ignored

Bug report

Bug description:

Hello,

Since Python 3.13, the following environment variables are no longer honored :

• REQUESTS_CA_BUNDLE
• SSL_CERT_FILE
• SSL_CERT_DIR

This is problematic in a corporate environment where a custom CA must be added. This was the only reliable way to make existing code, especially external libraries, trust a custom CA. It was easy and functional, and I don't understand why this feature is no longer here.

In addition, this new behavior is not sufficiently documented, and no workaround is proposed.

Thank you

CPython versions tested on:

3.13

Operating systems tested on:

Windows

まず、REQUESTS_CA_BUNDLE、SSL_CERT_FILE、SSL_CERT_DIR を設定した Windows の Python 3.13 で、報告された動作を再現します。証明書の設定がどのように処理されるかを追跡し、既存のコードが再びカスタム CA を信頼できるように、動作する修正または回避策を文書化します。