vertical grey "No HTML Message" alongside message body

Mon Sep 3 21:29:03 BST 2018

On Monday, September 3, 2018 1:15:44 PM MDT Jerome Yuzyk wrote:
> [KMail 5.8.3 on Fedora 28]
> 
> I just updated to the latest KMail this morning and now I have a vertical
> "No HTML Message" in a gray bar alongside the message body. I don't see how
> to remove it in any menus or settings.
> 
> How do I turn it off?

Apparently it's this bug: https://bugs.kde.org/show_bug.cgi?id=393421