Luckily, the original owner had the good smarts to take the battery out before they stored it away.
The last time there was a battery in the camera was in February 1972. So the camera has been sitting still for 38 years. I could see how an old battery would have made a mess of the battery compartment if the old one was still in it.
So it's nice to be able to get exactly the same kind of battery as was in the camera originally. Just snap it in place and rock'n'roll. I'm excited.