I was just trying to change my handle to a handle of another user. I believe that the user is inactive: they registered back in 2015 and were active for a couple of hours only (as confirmed by Codeforces API). The user didn't submit anything to the judge and didn't write any blog/comment/contest/etc. However, I'm still unable to change the nickname as the server states that the handle is currently in use.
So here comes my question: did anyone successfully change their handle to an already used one? Also, if you managed to do it, did the previous handle owner register in 2015 or was it earlier than 2015?