Log Message:
Update databases/elasticsearch to 5.2.2.

5.2.2

- The request circuit breaker, which track the size of in-flight
  requests, was not decrementing its counter when the connection was
  closed by the client before the response could be returned. This could
  result in no further requests being accepted until the node has been
  restarted. All users should upgrade to take advantage of this bug fix.
- The cgroup functionality (for reading OS stats for containers) had a
  bug in the regex for parsing /proc/self/cgroup which prevented nodes
  with multiple hierarchies from starting up.
- Requests which have been delayed by a shard lock might be executed
  later on a different thread which lacks the request context, resulting
  in the requests being incorrectly rejected as unauthorised.
- Removal of an undocumented syntax for include/exclude parameters in
  the terms aggregation broke certain aggregations in Kibana.

5.2.1

- When stored fields are configured with best_compression, we rely on
  JVM garbage collection to reclaim Deflater/Inflater instances. However
  these classes use little JVM memory but may use significant native
  memory, so if may happen that the OS runs out of native memory before
  the JVM collects these unreachable Deflater/Inflater instances.
- Certain queries can hold a reference to the IndexReader that was used
  to build them. When these queries are cached, this reference causes
  Lucene to hold onto segments long after they should have been deleted.