That is an African rock python. And not entirely true....

http://www.snopes.com/photos/animals/fencesnake.asp
The photographs displayed above evidently originated with the Silent Valley Game Ranch in South Africa, as we were informed in response to an inquiry sent there:

The snake had eaten an impala ewe and was trying to go through the electric fence when it was killed by the electric fence. The pictures were taken on Silent Valley Ranch in the Waterberg mountains of South Africa. If you go to the site you will see the images of the impala that was removed from the pythons stomach.