Merge: #21091: make is_attachment a method.

diff --cc Lib/email/message.py
index 124071d5e1d189c2796ecff77da5f8354a9c2eef,a179f8e374214d6115b791ef64af99847b064aa6..727cd1e865b75466ebe3fe8591e93ac8bd883277
--- 1/Lib/email/message.py
--- 2/Lib/email/message.py
+++ b/Lib/email/message.py
@@@ -938,13 -950,15 +939,12 @@@ class MIMEPart(Message)
              policy = default
          Message.__init__(self, policy)
  
--    @property
      def is_attachment(self):
          c_d = self.get('content-disposition')
 -        result = False if c_d is None else c_d.content_disposition == 'attachment'
 -        # XXX transitional hack to raise deprecation if not called.
 -        return _IsAttachment(result)
 +        return False if c_d is None else c_d.content_disposition == 'attachment'
  
      def _find_body(self, part, preferencelist):
-         if part.is_attachment:
+         if part.is_attachment():
              return
          maintype, subtype = part.get_content_type().split('/')
          if maintype == 'text':

diff --cc Lib/test/test_email/test_message.py
index 51ddf360996b18a96b3fff63ff27df8575a35a93,50e1a632c2b144b7c0fba9e8fae1c654eced46e5..d78049e315d04b1f7ddfaa03e49dffea7b6da951
--- 1/Lib/test/test_email/test_message.py
--- 2/Lib/test/test_email/test_message.py
+++ b/Lib/test/test_email/test_message.py
@@@ -722,15 -722,25 +722,15 @@@ class TestEmailMessageBase
  
      def test_is_attachment(self):
          m = self._make_message()
-         self.assertFalse(m.is_attachment)
+         self.assertFalse(m.is_attachment())
 -        with self.assertWarns(DeprecationWarning):
 -            self.assertFalse(m.is_attachment)
          m['Content-Disposition'] = 'inline'
-         self.assertFalse(m.is_attachment)
+         self.assertFalse(m.is_attachment())
 -        with self.assertWarns(DeprecationWarning):
 -            self.assertFalse(m.is_attachment)
          m.replace_header('Content-Disposition', 'attachment')
-         self.assertTrue(m.is_attachment)
+         self.assertTrue(m.is_attachment())
 -        with self.assertWarns(DeprecationWarning):
 -            self.assertTrue(m.is_attachment)
          m.replace_header('Content-Disposition', 'AtTachMent')
-         self.assertTrue(m.is_attachment)
+         self.assertTrue(m.is_attachment())
 -        with self.assertWarns(DeprecationWarning):
 -            self.assertTrue(m.is_attachment)
          m.set_param('filename', 'abc.png', 'Content-Disposition')
-         self.assertTrue(m.is_attachment)
+         self.assertTrue(m.is_attachment())
 -        with self.assertWarns(DeprecationWarning):
 -            self.assertTrue(m.is_attachment)
  
  
  class TestEmailMessage(TestEmailMessageBase, TestEmailBase):

diff --cc Misc/NEWS
index e4edc4cf39e8e09566862d4e81e755fbd14d5161,356021291a3598070549e27e989d9b81542f56b2..da74650a0f9462e7eb46b5ca74ca7e6620c6a42d
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -137,6 -32,11 +137,9 @@@ Core and Builtin
  Library
  -------
  
 -  a method.  Since EmailMessage is provisional, we can change the API in a
 -  maintenance release, but we use a trick to remain backward compatible with
 -  3.4.0/1.
+ - Issue #21091: Fix API bug: email.message.EmailMessage.is_attachment is now
++  a method.
+ 
  - Issue #21079: Fix email.message.EmailMessage.is_attachment to return the
    correct result when the header has parameters as well as a value.