bug#34639: 26.1; Custom themes break terminal when switching to org-mode

[Eli Zaretskii]

> From: Vika Shleina <kisik21@fireburn.ru>
> Date: Sun, 24 Feb 2019 20:44:43 +0300
> 
> 
> 1. emacs -Q
> 2. Write an org file with several headers
> 3. M-x customize-themes RET
> 4. Enable a custom theme
> 5. C-x b to the org file
> 6. Observer terminal artifacts appearing depending on contents (line and
> vertical character drift was observed in my case)
> 
> If it matters, I use the kitty terminal emulator:
> https://sw.kovidgoyal.net/kitty

Please show a screenshot of the artifacts, and please tell which theme
did you enable.

Also, does "C-l" remove the artifacts?

Thanks.