This question is closed as a dup.
I claim that Are raring arm packages available someplace? is actually the dup, it's the question that asks 'where are the packages'.
Upgrading raring to saucy on arm is a question about a problem that arose after I'd already taken the step called for by the duplicate target.
If you follow the link to the chat I had with muru, you will see that the problem is not at all that I didn't have the right old-releases URL in sources.list, but rather that something apparently arm-specific goes wrong with do-release-upgrade, which is not related to sources.list at all.