bpo-45195: Fix test_readline.test_nonascii() (GH-28329) (GH-28333)

Fix test_readline.test_nonascii(): sometimes, the newline character
is not written at the end, so don't expect it in the output.
(cherry picked from commit 797c8eb9ef511f0c25f10a453b35c4d2fe383c30)

Co-authored-by: Victor Stinner <vstinner@python.org>
diff --git a/Lib/test/test_readline.py b/Lib/test/test_readline.py
index e8fb8d2..59dbef9 100644
--- a/Lib/test/test_readline.py
+++ b/Lib/test/test_readline.py
@@ -255,7 +255,9 @@ def display(substitution, matches, longest_match_length):
             self.assertIn(b"matches ['t\\xebnt', 't\\xebxt']\r\n", output)
         expected = br"'[\xefnserted]|t\xebxt[after]'"
         self.assertIn(b"result " + expected + b"\r\n", output)
-        self.assertIn(b"history " + expected + b"\r\n", output)
+        # bpo-45195: Sometimes, the newline character is not written at the
+        # end, so don't expect it in the output.
+        self.assertIn(b"history " + expected, output)
 
     # We have 2 reasons to skip this test:
     # - readline: history size was added in 6.0