bug#20607: 24.5; Problem with overlays at same position but in different windows

[Eli Zaretskii]

> From: Oleh Krehel <ohwoeowho@gmail.com>
> Date: Mon, 18 May 2015 20:29:10 +0200
> 
> 
> Suppose I have two windows, WND1 and WND2, both displaying the same
> buffer. In WND1, there's an overlay from 1 to 2 with window property
> WND1 and display "ab". In WND2, there's an overlay from 1 to 3 with
> window property WND2 and display "abc".
> 
> Instead of the expected, I see "ab" in WND1, but "abcabc" in WND2.  When
> I `move-overlay' in the first window to 1-3, the glitch disappears, but
> I actually want the overlay to be 1-2, not 1-3. If I have to make it
> 1-3, I'd have to modify the display as well to include one more
> character from the buffer. I think it's better to fix the overlay logic
> rather than go for this work-around.

Please show the code to reproduce this.