bug#38560: 27.0.50; Emacs ignores input events during startup

[Juri Linkov <juri@linkov.net>]

>> > I have a configuration that takes 1-2 seconds to boot up.
>> >
>> > In previous versions (including the latest Emacs 26) it was rarely a
>> > problem because I could always start typing while the configuration
>> > finishes loading (e.g. C-x C-f first-chars-of-file-name).
>> >
>> > Emacs 27, however, ignores most of the keystrokes, so when I do that, by
>> > habit, I simply end up in the Scratch buffer with some of the last
>> > characters. E.g. "ile-name" in this example.
>
> There was some recent change related to discard-input, no?  Here:
>
>   commit 54c792ece6c20297571aa68c613075c8a8152bcc
>   Author:     Juri Linkov <juri@linkov.net>
>   AuthorDate: Sat Nov 30 23:33:41 2019 +0200
>   Commit:     Juri Linkov <juri@linkov.net>
>   CommitDate: Sat Nov 30 23:33:41 2019 +0200
>
>       * lisp/subr.el: Add discard-input to more functions.
>
>       * lisp/subr.el (read-char-from-minibuffer-insert-other)
>       (y-or-n-p-insert-other): Use discard-input in case of user mistake.
>       (do-after-load-evaluation): Add discard-input before calling 'message',
>       so in case of the active minibuffer, calling minibuffer-message will allow
>       sit-for to wait the complete timeout, because discard-input will discard
>       all initial events that prevent sit-for from waiting during startup.
>       https://lists.gnu.org/archive/html/emacs-devel/2019-11/msg00581.html
>
> Or maybe this one:
>
>   commit 4e4e5508582b1b5a2e738f4490400f2d78a5f343
>   Author:     Juri Linkov <juri@linkov.net>
>   AuthorDate: Sun Nov 17 23:51:55 2019 +0200
>   Commit:     Juri Linkov <juri@linkov.net>
>   CommitDate: Sun Nov 17 23:51:55 2019 +0200
>
>       * lisp/subr.el (read-char-from-minibuffer, y-or-n-p): Remove discard-input.
>
>       (do-after-load-evaluation): Replace run-with-timer with run-with-idle-timer
>       to give a chance for the minibuffer to handle initial events before sit-for.
>       https://lists.gnu.org/archive/html/emacs-devel/2019-11/msg00581.html

I already created a fix for this a week ago in bug#38457,
but you didn't allow me to install the fix.  That's unfair
to blame me for problems that you don't allow to fix.