wrong result (correct algorithm)

I would like to give some feedback about ...

From: http://www.checkio.org/mission/network-loops/solve/

HTTP_USER_AGENT:

Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.2357.124 Safari/537.36

the program work in my machine (same python 2.7 version) ,the same input is return another result in the server ( wrong ordre in recursion may be the server execute the calls in threads or paralléle processus )