SOLR-5645: A SolrCore reload via the CoreContainer will try and register in zk again with the new SolrCore.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_6@1559581 13f79535-47bb-0310-9956-ffa450edef68
SOLR-5636: SolrRequestParsers does some xpath lookups on every request, which can cause concurrency issues. 

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_6@1559582 13f79535-47bb-0310-9956-ffa450edef68