While the end-user player license remains the same as previous versions, Xonotic has added to it's developers license a no-pedophile rule .
*[1]

Some might say "this isn't a license change".
A license is permission. Xonotic has voted on, and agreed to this new rule.
It may very well be found by a court to be a license change for developers.

>THEY CAN'T DO THAT
They did.
>THE GPL DOESNT ALLOW THAT!
Got 500k to fight it out?
Also they'll claim their change isn't in the end-user license (but it is an enforced rule, which was voted on and agreed to by the other copyright holders in the Xonotic 0.9 team, and the steering committee): which may amount, by court ruling, to a change in the developer license.
>THIS ISNT A LICENSE CHANGE
It is clear that the community has voted on, including the other copyright holders (though derivative) of various pieces, to enact a no-pedophile rule for Xonotic 0.9 etc.

It cannot be said that it is totally non-enforceable: the copyright holders to the derivative work Xonotic 0.9 (derivative of earlier versions of Xonotic, which is derivative of Nexuiz, which is derivative of an earlier half-life mod, All of which is a derivative work of Quake1 (the engine especially, and much of the Quake C (game) code in Xonotic)), have made clear their feelings about pedophiles working on their project, and have voted to exclude atleast one person.