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

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_5x@1626751 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5969: remove unnecessary code

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_5x@1626754 13f79535-47bb-0310-9956-ffa450edef68