I used the wikitext editor to edit a post. The edit succeeds, but it doesn't return it in the right format, so it doesn't correctly re-render.
The request is
It is returned as:
You can see that it's returning wikitext (the same format as the input from the editor). It should be returned fixed HTML, since the edit is done, and we're now going to normal view mode.
The database/cache write itself is fine AFAICT, and a page reload will show everything normally again.
This is probably caused by the recent format refactoring, and is currently on Beta: http://en.wikipedia.beta.wmflabs.org/wiki/Talk:Flow .