bug#41640: 28.0.50; shell startup very slow when init file is used

[Jan Synacek <jsynacek@redhat.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Pip Cet <pipcet@gmail.com>
>> Date: Thu, 04 Jun 2020 21:21:00 +0000
>> Cc: 41640@debbugs.gnu.org
>> 
>> diff --git a/lisp/comint.el b/lisp/comint.el
>> index ea06f8af87..4354a155c3 100644
>> --- a/lisp/comint.el
>> +++ b/lisp/comint.el
>> @@ -809,18 +809,10 @@ comint-exec
>>        (goto-char (point-max))
>>        (set-marker (process-mark proc) (point))
>>        ;; Feed it the startfile.
>> -      (cond (startfile
>> -	     ;;This is guaranteed to wait long enough
>> -	     ;;but has bad results if the comint does not prompt at all
>> -	     ;;	     (while (= size (buffer-size))
>> -	     ;;	       (sleep-for 1))
>> -	     ;;I hope 1 second is enough!
>> -	     (sleep-for 1)
>> -	     (goto-char (point-max))
>> -	     (insert-file-contents startfile)
>> -	     (setq startfile (buffer-substring (point) (point-max)))
>> -	     (delete-region (point) (point-max))
>> -	     (comint-send-string proc startfile)))
>> +      (when startfile
>> +        (comint-send-string proc (with-temp-buffer
>> +                                   (insert-file-contents startfile)
>> +                                   (buffer-string))))

This patch removes the slowness.