bug#57129: 29.0.50; Improve behavior of conditionals in Eshell

[Eli Zaretskii]

> Cc: larsi@gnus.org, 57129@debbugs.gnu.org
> From: Jim Porter <jporterbugs@gmail.com>
> Date: Sat, 20 Aug 2022 11:03:27 -0700
> 
> In addition to the changes to temporary file name generation, I think it 
> would be useful for Eshell to kill the temporary buffer too. If you use 
> this feature in Eshell a lot, the temporary buffers could pile up, 
> consuming memory for no real benefit. (A user who wanted the buffer to 
> stick around would probably redirect to a non-temporary file, or even 
> just to a buffer.) Attached is a patch to do this.

That makes sense, of course, but why not use with-temp-buffer in the
first place?