LUCENE-1376: catch BG merge exceptions even if all merges finish before FG thread (running optimize) advances to while loop
LUCENE-1376: catch BG merge exceptions even if all merges finish before FG thread (running optimize) advances to while loop

git-svn-id: 4c5078813df38efa56971a28e09a55254294f104@691964 13f79535-47bb-0310-9956-ffa450edef68

apache/solr,apache/solr,apache/solr,apache/solr,apache/solr