This is very wierd. I go: `~/openarena-0.8.1$ ./openarena` and it loads the version 0.7.7. However it does read 0.81 servers and connect to them and if I leave that server, OA will launch 0.81 like it should. So the worst problem is that I can't use the bots-filter. I've noticed that if I use the "Open arena" mod in the mods list it launches 0.77 so maybe that's the problem.
Noteworthy is that I do have OA 0.77 installed as well but in a completely different part of the system. And to my knowledge there are no links between them.
It should be openarena.x86_64 or openarena.i386.
You can also try renaming ~/.openarena and launch OA and if it works fine, then the problem is in that directory.