This should keep people from getting "hit in the face" with errors when they try to use the haystack ES backend. :-) pyelasticsearch/pyelasticsearch#86
We removed the internally unused and undocumented to_python in pyelasticsearch 0.4. I copied the version from 4266529eaefb96af0a8e99017740cbb56608dbe4 and removed the `six` dependencies.
I'm actually not sure why haystack needs to call anything like to_python itself; pyelasticsearch implicitly converts most data types, though datetimes are a notable hole. But this is a quick fix.