"this is an early experiment in carrying out an Xz attack by using an agent to build trust"

Is this confirmed? There is the message from somebody claiming to be the original contributer claiming to have been hacked, but that was weird (1 h old github account) so other scenarios seem possible

a) really a agent going off the rails

b) the contributer trying to cover up that he let an agent run wild and now made more misstakes along the way

So yes, it seems like an attack to me, but it is far from clear what really happened.