Due to a silly typo the yaboot-1.3.15.tar.gz was pretty much useless. I’ve updated the tarball. Sorry all.

MD5:            6027909805490b644816e800aba9f5a6  yaboot-1.3.15.tar.gz
SHA1:	7f394d81522fe1e7aed9daf8ad06568d6b74267f  yaboot-1.3.15.tar.gz

Thanks to acrux for pointing out the problem.