elasticsearch/elasticsearch — pull request #6531 by GaelTadh (2014-06-17 11:24:16+00:00)
Title: Mapping: Fix delete mapping race condition.

If multiple clients attempted to delete a mapping, or a single client attempted to delete a mapping as an index is being
created a NPE could be observed in the MetaDataMappingService. This fix makes sure we don't try to access a null indexMetaData object.
Also add a test to spawn multiple create and delete threads to provoke this race condition.

Closes #5997