Ok I tried and have to say it's pretty weird behaviour.
I've enable beta channel in developers module, it stated it will update to 14.0.A1. Ok, clicked on update and then it update to all the version mentioned. So why not doing this when displaying the stable?
I planned to stop on 13.1.0 then but at 13-RC3 I get a "Site is temporarily unavailable due to scheduled maintenance, please try again in a minute." message now, so I got stalled. Nothing in the logs, neither server side nor from Una. Only one warning from AqbBannersModule, that's it.
Update: I am on 13.1.0 now, had to remove the _bx_maintenance file and all went well from there on.