bug#29198: Cursor fringe arrow indicator not updating.

[Eli Zaretskii]

> Date: Tue, 07 Nov 2017 11:57:49 -0800
> From: Keith David Bershatsky <esq@lawlist.com>
> 
> The following code works fine with no user configuration in Emacs 25.3.  
> However, it does not work well with the current version of the master branch. 
>  The overlay arrow indicator is not updating as the user moves up or down in 
> the buffer with the keyboard arrow keys.
> 
> Step 1:  Open an Emacs built from the current master branch.
> 
> Step 2:  Got to the scratch buffer and evaluate the code below.
> 
> Step 3:  Maneuver up and down with the arrow keys navigating the code below.  
> The fringe bitmap indicator should track the vertical cursor position, but it 
> does not work.

Does it update if you type "M-x"?  If it does, you aren't triggering a
thorough enough redisplay.