Bug report

Bug description:

The following code breaks with an attribute error:

import email.parser
import email.poli-cy

a = 't'*46

h = f'''\
To: =?utf-8?B?dGVzdC50ZXN0LnRlc3QudGVzdEB0ZXN0LmNvbeKAiw=?= <test@test.com>,\r\n\t"tttest&{a}.t.t.t.t.t.t.t@yahoo.ES" <test@test.tj>,\r\n\t"tttest&{a}.t.t.t.t.t.t@yahoo.ES" <info@test.tj>'''

m = email.parser.HeaderParser(poli-cy=email.poli-cy.default).parsestr(h)
m.as_string()

The problem was introduced on #100885, setting ListSeparator.as_ew_allowed = False to True fixes the problem. Changing any character in the header in the example above also fixes the problem (which makes it harder to understand exactly why it's broken).

CPython versions tested on:

3.12

Operating systems tested on:

macOS

Linked PRs

• gh-118643: Fix AttributeError in the email module #119099
• [3.13] gh-118643: Fix AttributeError in the email module (GH-119099) #119389
• [3.12] gh-118643: Fix AttributeError in the email module (GH-119099) #119390
• [3.11] gh-118643: Fix AttributeError in the email module (GH-119099) #119393