This is a bit contrived, but a bug nonetheless:
- Go to [[testwiki:Sections galore]]
- Observe the wikitext source, then edit in VE
- Let's say you want to rewrite this article, so you select the entire lead and first section (from "Lead..." to "...core") and type some new text over it
- Make your new text into a heading
- Review changes
The category inclusion (which was previously before the "Apple" heading) becomes part of the new heading, which is silly from the point of view of a wikitext user.