Can you create one?  Retrospectively, I mean? It'd be a good place to write a simple description of the problem this particular PR is solving, and it'd set a good example for future commiters (including, ahem, myself, as I often forget to write these issues up ahead of time, and I know Matt and Jeff are eager for us to be a bit more disciplined).  

If you don't want to, um, that's fine too :-)