elasticsearch/elasticsearch — pull request #8955 by dakrone (2014-12-15 13:39:46+00:00)
Title: [CORE] Remove IndexEngine

IndexEngine was an abstraction where we had index-level engines (instead
of shard-level) that could store meta information about the index. It
was never actually used by Elasticsearch, and only there for plugins.

This removes it, because it is a confusing abstraction and not needed,
no plugins should be implementing their own IndexEngines.