bug#25792: 26.0.50; Scroll-margin working incorrectly when scrolling down if show-trailing-whitespace is t

[npostavs]

severity 25792 minor
tags 25792 confirmed
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Alexander Miller <alexanderm@web.de> writes:

> Only scrolling down is affected. The issue first appeared when I
> recompiled emacs roughly 1 week ago and has persisted over multiple
> recompilations on 2 different laptops (both running Antergos & Xfce), so
> my guess is that it's an issue in the current emacs master.

This seems to be caused by [1: b9be4c14e8], it only happens when the
window has partial lines (i.e., (zerop (cadr (cl-floor
(window-screen-lines)))) is non-nil).  Not sure how
show-trailing-whitespace affects this, but it does.

1: 2017-02-02 21:21:18 -0500 b9be4c14e89f5cec08a7a0f0d24033e0e6ff5ef0
  Fix scrolling with partial lines