Editing an answer to a question while writing an answer makes the "Answer this Question" button reappear

Question

I was writing an answer (had text in the textbox) to Feedback Requested: Stack Overflow design update and noticed an answer up above that needed a little work. I edited the answer, and scrolled down to see this:

Steps to reproduce:

1. Find a question with a bunch of answers, like the one mentioned above or How do JavaScript closures work?.
2. Click the "Answer this Question" button.
3. Tell the scary dialog that you know what you're doing.
4. Type stuff in the box (optional)
5. Scroll up and click edit on another answer
6. Cancel the edit (escape) or go through with it, doesn't matter
7. Observe bug at bottom of page.
8. Repeat from step 5 and make things more broken:

   

9. Go fix bug.

Answer 1

Fix is going out with build 2014.12.?.2813 on meta and 2014.12.?.2057 on sites.