Using the current working directory won't work, since we do not chdir into the keg.

Under normal circumstances, you could just call find without an explicit receiver since Keg inherits from Pathname. However, find calls `self.class.new` when instantiating the objects it yields, and the checks in the Keg constructor will raise an exception since those objects are not kegs.

So I would suggest `Pathname.new(self).find`.