When I hit "edit" on this question the editor shows the source not of the current revision, but the one before it.
I can reproduce this in multiple browsers, both logged in and anonymously and another user confirmed it in chat.
I found it originally via the new review queue, that much I'm certain of. I thought I'd backed out of an improve in the new review queue on this one and done it from the question page itself in the end, after it had already been approved but the timestamps in the revision history and the log on the suggested edit disagree there so I might be misremembering that.