bug#56025: 29.0.50; em-extpipe-test-2 times out on EMBA and Cygwin

[Eli Zaretskii]

> Date: Thu, 23 Jun 2022 21:18:24 -0400
> From: Ken Brown <kbrown@cornell.edu>
> 
> 2. On Cygwin and some other platforms, including Solaris 11.4 I think, it 
> actually takes a third C-d, for reasons explained in the email thread 
> starting 
> at https://cygwin.com/pipermail/cygwin/2022-June/251672.html.  We're probably 
> going to change this on Cygwin, but that still leaves other platforms.
> 
> The following patch resolves both issues:
> 
> diff --git a/lisp/eshell/esh-io.el b/lisp/eshell/esh-io.el
> index 3644c1a18b..1c4131cb07 100644
> --- a/lisp/eshell/esh-io.el
> +++ b/lisp/eshell/esh-io.el
> @@ -276,8 +276,8 @@ eshell-close-target
>      ;; If we're redirecting to a process (via a pipe, or process
>      ;; redirection), send it EOF so that it knows we're finished.
>      ((eshell-processp target)
> -    (if (eq (process-status target) 'run)
> -       (process-send-eof target)))
> +    (while (eq (process-status target) 'run)
> +      (process-send-eof target)))

Please add there comments explaining why this is done, or at least
point to relevant messages in this bug's discussion (NOT just to the
bug number, as the discussion is long and it will be hard to
understand what part of it is relevant).  Such "tricky" code should
always have comments explaining it.

Thanks.