fix false assert trip; fix LTC to be 'sticky' in how it changes the live IWC settings for flush triggers

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1595300 13f79535-47bb-0310-9956-ffa450edef68
woops, remove nocommit

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1595301 13f79535-47bb-0310-9956-ffa450edef68