I also looked this up, and found the original paper that coined the term, which starts:
> The "Wolf Fence" method of debugging time-sharing programs in higher languages evolved from the "Lions in South Africa" method that I have taught since the vacuum-tube machine language days. It is a quickly converging iteration that serves to catch run-time errors.
It stipulates that the state of Alaska has got exactly one wolf, so you build a fence across the middle of the state to find on which side wolf would howl, then subdivide the problem, etc...
I'm assuming in your case the wolf got replace with a lion and Alaska with South Africa.
I found I knew of it under a different name: binary search debugging. Git includes built-in support under the bisect command.