Hostname won't change from "Team Fortress 2 Arena Server"

Why does mapcycle.txt change my HostName? mapcyclefile “mapcycle.txt” changes my host name in "Team Fortress 2 Arena Server" and I can't change it.

If I try to change my hostname it doesn't change. O.O
hostname "host name here" line doesn't work...

arena maps load a seperate config called arena_config.cfg

open this file, remove the host name line. save. and yer done.

Or use rcon?

you would need to do that every time an arena map came up mooga...

Yes you would.  But he said he was just trying to change via the command.  The reason it wouldn't work is because unless the server is local, you need to rcon it.  Fixing the arena config by removing the hostname line is probably the best bet