give MDW verbosity when it throws deterministic exception

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1625541 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5958: add more efficient test

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1625543 13f79535-47bb-0310-9956-ffa450edef68