SOLR-5281: IndexSchema log message was printing '[null]' instead of '[<core name>]' (merge trunk r1526972 and 1527074)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_5@1527080 13f79535-47bb-0310-9956-ffa450edef68