bug#31855: 27.0.50; Async shell command finished message not visible any more

[Eli Zaretskii <eliz@gnu.org>]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Date: Sat, 16 Jun 2018 07:12:50 +0200
> 
> In emacs25 -Q, I type, for example, M-! t r u e SPC & <return>, and the
> echo area displays "true: finished".
> 
> In master emacs -Q, doing the same gives you no visible feedback any
> more.  A message is logged in *Messages*, but it seems to be dismissed
> immediately.

Daniel, this seems to be due to your recent changes in keyboard.c.  If
I make the change below, which reverts a small part of your changes,
the problem is gone:

diff --git a/src/keyboard.c b/src/keyboard.c
index 5409918..76097e8 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -8999,7 +8999,7 @@ read_key_sequence (Lisp_Object *keybuf, Lisp_Object prompt,
   /* These are no-ops the first time through, but if we restart, they
      revert the echo area and this_command_keys to their original state.  */
   this_command_key_count = keys_start;
-  if (INTERACTIVE && is_replay)
+  if (INTERACTIVE && t < mock_input)
     echo_truncate (echo_start);
   is_replay = true;