LUCENE-5863: port forward. the nocommit is intentional.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1624107 13f79535-47bb-0310-9956-ffa450edef68
improve test debuggability

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1624108 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6452: CHANGES.txt entry

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1624117 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5935: remove terrifying yet stale TODO

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1624128 13f79535-47bb-0310-9956-ffa450edef68