[3.12] gh-87720 Fix additional header refolding-quoting edge case (GH-134271) (#159066)

gh-87720 Fix additional header refolding-quoting edge case (GH-134271)

In this case, the higher level syntactic unit fit on the remainder of
the line in un-encoded format, and that higher level unit was
not a ptext or vtext, so the encoding check failed.  To fix this, we
look inside the current unit to see if has anything that was
originally encoded.
(cherry picked from commit 5a22a62)

Co-authored-by: R. David Murray <rdmurray@bitdance.com>

Author: miss-islington

Lib/email/_header_value_parser.py

@@ -168,6 +168,14 @@ def comments(self):
             comments.extend(token.comments)
         return comments
 
+    def contains_token_type(self, *token_types):
+        if self.token_type in token_types:
+            return True
+        for t in self:
+            if t.contains_token_type(*token_types):
+                return True
+        return False
+
     def fold(self, *, policy):
         return _refold_parse_tree(self, policy=policy)
 
@@ -928,6 +936,9 @@ def pop_trailing_ws(self):
     def comments(self):
         return []
 
+    def contains_token_type(self, *token_types):
+        return self.token_type in token_types
+
     def __getnewargs__(self):
         return(str(self), self.token_type)
 
@@ -2819,7 +2830,7 @@ def _refold_parse_tree(parse_tree, *, policy):
             continue
         tstr = str(part)
         if not want_encoding:
-            if part.token_type in ('ptext', 'vtext'):
+            if part.token_type == 'ptext' or part.contains_token_type('vtext'):
                 # Encode if tstr contains special characters.
                 want_encoding = not SPECIALSNL.isdisjoint(tstr)
             else:

Lib/test/test_email/test__header_value_parser.py

@@ -3096,6 +3096,11 @@ def test_address_list_with_specials_in_encoded_word(self):
              'A =?utf-8?q?v=C3=A9ry?= long name\n'
              ' containing =?utf-8?q?a=2C?= comma\n'
              ' <to@example.com>\n'),
+            ('=?utf-8?Q?a=2C=20123456789012345678901234567890123456?='
+                ' <abc@example.com>',
+             '=?utf-8?q?a=2C?=\n'
+             ' 123456789012345678901234567890123456\n'
+             ' <abc@example.com>\n'),
         ]
         for (to, folded) in cases:
             with self.subTest(to=to):

Misc/NEWS.d/next/Library/2026-10-08-16-18-43.gh-issue-87720.Elqdl9.rst

@@ -0,0 +1,3 @@
+Fixed error in :mod:`email` new policies where header folding failed to
+detect the need to re-quote text obtained from encoded words in certain
+cases.