LUCENE-5958: handle illegalstateexception 'checks' by IW as well

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1626750 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5969: remove unnecessary code

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1626753 13f79535-47bb-0310-9956-ffa450edef68