SOLR-6732: fix back-compat issue with unit test to verify solution

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_10@1640432 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6732: mention in changes

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_10@1640434 13f79535-47bb-0310-9956-ffa450edef68