Steps to reproduce
Open any answerable question.
Put "Yes" in the text area, mark the community wiki checkbox, and click "Post Your Answer."
You get the following error message.
Oops! Your answer couldn't be submitted because:
- only Joel Spolsky can post answer with less than 30 characters; you entered 3
The community wiki checkbox was reset in the process.
If you just fix your answer and post it again, it won't be Community Wiki. This is clearly unexpected behavior, and it can have unpleasant consequences if overlooked.