LUCENE-5242: DirectoryTaxonomyWriter.replaceTaxonomy did not fully reset its state

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1525894 13f79535-47bb-0310-9956-ffa450edef68
fix windows test failure in TestImplicitCoreProperties

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1525935 13f79535-47bb-0310-9956-ffa450edef68