- Create a page with a normal account
- Edit this page with a account with the right bot, set the botflag for the edit
- Go to settings, activate the option, that you only can see the last edit of a page in your watchlist
- Load your watchlist: You can see the edit of the bot now
- Now use hidebots. The bot edit is now gone (as expected). But you can't see the edit of the user before now
This is a huge disadvantage: this makes the botflag actually a bit useless, since if a bot edit a lot of pages, and people use the setting, that they can only see the last edit of a page, it blocks them from using hidebots, since they would miss real changes then.
Version: Tested at beta-dewiki. If you want to check this out, just list https://de.wikipedia.beta.wmflabs.org/w/index.php?title=Beotest&curid=3399&action=history at your watchlist.