bug#50176: [PATCH] 28.0.50; repeat-mode does not clear echo-area after timeout

[Gabriel]

Description:
When repeat-mode is enabled and a repeat-exit-timeout is set, the
echo-area is not cleared in case the echo-area has some content and a
single repeat-command is executed.

Steps:
1) emacs -Q (from master branch)
2) eval
    (setq repeat-exit-timeout 1)
    (repeat-mode 1)
3) create some windows with 'C-x 2' and 'C-x 3'
4) 'C-x'
5) wait prefix "C-x" to appear on echo-area
6) 'o' (echo-area will now contain "C-x o [Repeat with o, O]")
7) wait a few seconds so 'repeat-exit-timeout' takes effect
Expected: the echo-area is cleared
Actual: the echo-area is not cleared

If 'o' is pressed again, it will run 'self-insert-command' even though
the echo-area is still showing "C-x o [Repeat with o, O]".

Now repeat steps 1-5 but press 'o' quickly to invoke the repeat command
multiple times (which will trigger other-window multiple times). The
echo-area changes to "Repeat o, O" and is properly cleaned after
'repeat-exit-timeout' seconds.

Patch:
I created a simple patch that seems to fix this probem. The
'string-prefix-p' was replaced with 'string-match-p' to handle cases
where echo-area contains some other message. This check seems very poor,
though, so any better approach is welcome.

>From e6de15337bf4516740c0e790f6a2bfb3deaf9b5b Mon Sep 17 00:00:00 2001
From: Gabriel do Nascimento Ribeiro <gabriel376@hotmail.com>
Date: Mon, 23 Aug 2021 19:05:58 -0300
Subject: [PATCH] Fix to clear echo-area after repeat-exit-timeout.

* lisp/repeat.el (repeat-echo-message): Use 'string-match-p'
to handle cases where echo-area contains other messages.
---
 lisp/repeat.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/repeat.el b/lisp/repeat.el
index cec3cb643a..054eacf8ec 100644
--- a/lisp/repeat.el
+++ b/lisp/repeat.el
@@ -474,7 +474,7 @@ repeat-echo-message
         (if (current-message)
             (message "%s [%s]" (current-message) mess)
           (message mess)))
-    (when (string-prefix-p "Repeat with " (current-message))
+    (when (string-match-p "Repeat with " (current-message))
       (message nil))))
 
 (defvar repeat-echo-mode-line-string
-- 
2.32.0