SOLR-5615: Deadlock while trying to recover after a ZK session expiration.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_6@1557811 13f79535-47bb-0310-9956-ffa450edef68
SOLR-5615: Add CHANGES entry to 4.6 branch

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_6@1557812 13f79535-47bb-0310-9956-ffa450edef68
SOLR-5615: Fix CHANGES mismerge

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_6@1557814 13f79535-47bb-0310-9956-ffa450edef68