bug#38176: 27.0.50; pdf-tools images do not display

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Sun, 17 Nov 2019 19:25:34 +0100
> Cc: 38176@debbugs.gnu.org
> 
>         (when (or (= (window-vscroll) (image-scroll-up arg))
> 
> It's comparing the output of window-vscroll (which returns the position
> in number-of-lines, not pixels) with the return value of
> image-scroll-up, which returns a value in pixels.  It's not documented
> at all what the latter function is supposed to return, so it looks like
> a bug to me that pdf-tools relies on it.

This was supposed to be fixed already, see bug#37578.