SOLR-4578: CoreAdminHandler#handleCreateAction gets a SolrCore and does not close it in SolrCloud mode when a core with the same name already exists.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_2@1458098 13f79535-47bb-0310-9956-ffa450edef68