Validation condition is not correct.

I would like to give some feedback about ...

From: https://checkio.org/mission/the-longest-palindromic/solve/

HTTP_USER_AGENT:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2486.0 Safari/537.36 Edge/13.10586

On the test case#4, I think the input is 'aaaa' however validation condition is to returning right answer is 'aaaaa' instead of 'aaaa'.