test: update test assertion for line wrapping in email messages

Author: zangjiucheng

Lib/email/contentmanager.py

@@ -143,7 +143,7 @@ def _encode_base64(data, max_line_length):
 
 
 def _encode_text(string, charset, cte, policy):
-    # max_line_length 0/None means no limit, ie: infinitely long.
+    # If max_line_length is 0 or None, there is no limit.
     maxlen = policy.max_line_length or sys.maxsize
     lines = string.encode(charset).splitlines()
     linesep = policy.linesep.encode('ascii')

Lib/test/test_email/test_message.py

@@ -1022,7 +1022,7 @@ def do_test_no_wrapping_max_line_length(self, falsey):
         msg.set_content(body)
 
         raw = msg.as_bytes()
-        self.assertNotIn(b"\r\n ", raw,
+        self.assertNotIn(b"=\n", raw,
                          "Found fold indicator; wrapping not disabled")
 
         parsed = message_from_bytes(raw, policy=policy.default)