email.utils.formataddr incorrect handling of unicode names with comma

Bug report

When email.charset is configured to produce 8bit content, calling email.utils.formataddr can result in corrupted output from formataddr. Here's example code:

import email.charset
import email.utils

email.charset.add_charset('utf-8', None)
print("To: " + email.utils.formataddr(('Foo, Bar', 'foo@example.com')))
print("To: " + email.utils.formataddr(('Fôo, Bar', 'foo@example.com')))

Expected output:

To: "Foo, Bar" <foo@example.com>
To: "Fôo, Bar" <foo@example.com>

Actual output:

To: "Foo, Bar" <foo@example.com>
To: Fôo, Bar <foo@example.com>

Your environment

• CPython versions tested on: 3.11.1
• Operating system and architecture: Fedora 37 x86_64

Linked PRs

• gh-155881

首先在 CPython 3.11.1 上執行提供的 email.charset 和 email.utils.formataddr 重現，然後檢查 formataddr 如何處理包含逗號的非 ASCII 顯示名稱。當輸出與預期的兩行 To 相符，且回歸測試涵蓋已設定的 8bit 情況時，即代表完成。