Avoid retrieving duplicate documents by ID

[bkis]

/dicts/foo/restful/ids?ids=bar&ids=bar&ids=bar&ids=bar returns the same document four times. I am aware this doesn't mean the end of the world, but maybe something close.

This just ensures the ids list that came from the controller and is passed to elasticsearch-dsl's doc.mget method contains only unique IDs by doing a quick list(set(ids)).

Technically, set(ids) would be enough, as elasticsearch-dsl just loops over the elements of any sequence, but the docs argument of mget is documented as a "list of ids of the documents to be retrieved or a list of document specifications" (although the type hint for docs is List[Dict[str, Any]], so I guess they're just being sloppy with their docs and/or type hints anyway).