bug#25863: 25.1; garbage display by small image

[Eli Zaretskii]

> From: ynyaaa@gmail.com
> Date: Sat, 25 Feb 2017 00:39:15 +0900
> 
> Evaluating the form below, the lower part of 'g' shape
> remains to be displayed.
> 
> (progn
>   (switch-to-buffer (generate-new-buffer "temp"))
>   (insert-image (create-image (concat "P4\n8 22\n" (make-string 22 127))
>                               'pbm t))
>   (insert ?g)
>   (redisplay)
>   (delete-char -1))

Not reproducible here.