[14.21] Desync on join when server generaly has no admins

[Miyu]

Basically if the server has no admins (you demote the only admin, which is the first player that connects) you will get in a desync loop when you try to connect to the server.
I used the headless linux64 0.14.21.

Steps to reproduce:

1. Create a server with a new map.
2. Join the server (the first player is made an admin)
3. Demote that player (or self-demote)
4. Leave the server
5. Reconnect

When you reconnect you will get in a desync loop, I have not tried if other players can join, but I (the demoted admin) couldn't join back in. The only way to fix is to promote an admin.
Desync report:

desync-report-2017-01-18_11-42-17.zip

[Rseding91]

Fixed for 0.15.