Only make one request for supply point cases

http://manage.dimagi.com/default.asp?115038
More concise (six less characters). And it's about twice as fast, but I doubt that matters here:
```sh
$ python -m timeit '{v: v for v in range(100)}'
100000 loops, best of 3: 11.6 usec per loop
$ python -m timeit 'dict((v, v) for v in range(100))'
10000 loops, best of 3: 23.5 usec per loop
```