bug#50560: 28.0.50; 'insert-file-contents-literally' on multibyte buffers

[Eli Zaretskii]

> From: Augusto Stoffel <arstoffel@gmail.com>
> Date: Mon, 13 Sep 2021 08:58:06 +0200
> 
> I thought 'insert-file-contents-literally' literally just inserted the
> file contents, as bytes, but I noticed that in the following code
> 
>     (create-image
>      (with-temp-buffer
>        (set-buffer-multibyte nil)
>        (insert-file-contents-literally "picure.jpg")
>        (buffer-substring-no-properties (point-min) (point-max)))
>      nil t)
> 
> the call to 'set-buffer-multibyte' is really essential.

It is only essential for some very specific uses of the resulting
buffer, but definitely not for all.