I doubt that the nickel coating had much to do with this failure other than possibly being more prone to mating with the jacket material. I suspect a flaw in the case forming process causing a slight fold at the failure junction, super hardening it during the remainder of the forming process and causing it to fail before the case length even expanded to fill the chamber. Add this to a somewhat bonded bullet/case neck and voila we have this failure.
That's a new one for me too, Ted, never had one do that. I'm going to guess this is a quite old factory round, that's been shelved for a decade or two?? I'm sure there are metallurgists who can confirm or deny this, out there, but I've heard that nickel plating of brass will cause the brass to lose it's elasticity and take on more properties of the nickel over extended periods of time. This is also what happens when the bullet welds it's self to the case neck, that there is actually a transfer of elements between the two metals, or possibly just from the nickel to the copper of the jacket material.
I know copper will, for a fact, draw carbon from a brush if left in contact and unmoved for an extended period of time.