bpo-45195: Fix test_readline.test_nonascii() (GH-28329) (GH-28984)

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 797c8eb)

Co-authored-by: Victor Stinner <vstinner@python.org>

Author: miss-islington

Lib/test/test_readline.py

@@ -232,7 +232,9 @@ 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

Misc/NEWS.d/next/Tests/2021-09-14-13-16-18.bpo-45195.EyQR1G.rst

@@ -0,0 +1,3 @@
+Fix test_readline.test_nonascii(): sometimes, the newline character is not
+written at the end, so don't expect it in the output. Patch by Victor
+Stinner.