min/max for unint facets without constraints gives Exception

[emidln]

When searching using the facet keyword, specifying an UnsignedIntegerField but no corresponding entry to facet_constraints for that UnsignedIntegerField causes Cloudsearch to return facet information about the minimum and maximum values for that field. This is not handled by the backend in _process_results.

To test, do something like this inside a repl:

search(my_index, "some_query", facet=['myuint_field'])

You'll get an exception that you can examine with import pdb; pdb.pm()