It was part of the original documentation for Fractint - software for generating Mandelbrot and Julia sets, substantially expanded later on - which was many people's first exposure to the concept of open source.
GNU was already operational but ineffective, which was why Linux (which was more focused on something that worked and less on maintaining ideological purity) took off like a rocket shortly after Linus released it.
I know you know your history and I know that you're smart because of the many many comments of yours I've read over the years but I have to disagree with you.
The whole point of GNU was to make a free UNIX. They logically started with the tools to do this. Editor, then compile tool-chain, standard library, user-land tools, … the kernel was to come eventually. But kernels are _hard_, not necessarily because writing a pre-emptive scheduling system with virtual memory is difficult (it is) but because 50% of the OS is drivers and for that you need hardware documentation. Besides a kernel ideally needs CPU support.
The i386 was the first mass market cheap CPU to provide a large (virtual) addressable space, memory isolation (rings 0..3), and so on. This was when Windows took off if you'll remember and when Novell was able to write a decent networking server, and Xenix, and OS/2, and I even remember buying a book that presented the source code for a 32-bit OS on i386 that I bought and marvelled at and lost somewhere on my travels.
Linus wrote Linux _at the right time_ for the i386, and built upon GNU. He famously said that it was a small project, not big and fancy like GNU -- you can Google the exact quote. Also, Linux uses GPLv2!, the socio-legal hack that Stallman and co. came up with, so Linux was _doubly_ dependent on the fruits of GNU. Why do you think Stallman and many others to this day want us to call our systems GNU/Linux? So I disagree -- though lacking a kernel, GNU provided a hell of a lot so I wouldn't call it ineffective just because they didn't manage to make a kernel.
It is true that Linus is more pragmatic than ideological. Having said that I think it is distro vendors that package the kernel with binary blobs, I'm not sure if blobs come with the kernel but I'm totally open to correction on this front, it's been a very long time since I looked under the hood! But I reckon Linux's success was due more to Linus's engineering skills, social skills, coding skills, taste, building on the work of Intel, PC architecture, and GNU.
Sorry about leaving this excellent comment without a reply. I completely agree, and overstated things by saying GNU was moribund.
The great thing about Linux was not just it was accessible and so on, but that it fit on (iirc) 4 1.44mb floppy disks and so you could get it up and running in under an hour.
For anyone who's still as confused as I am, apparently the connection between Stone Soup and open source is that the group who developed Fractint (one of the first open source programs and still used today) was called the Stone Soup Group.
GNU was already operational but ineffective, which was why Linux (which was more focused on something that worked and less on maintaining ideological purity) took off like a rocket shortly after Linus released it.