Spell checking index needs to be cleared when rebuilt, otherwise older non-existent terms are suggested

git-svn-id: https://svn.apache.org/repos/asf/lucene/solr/trunk@533515 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/solr/handler/SpellCheckerRequestHandler.java

@@ -152,6 +152,7 @@ public class SpellCheckerRequestHandler extends RequestHandlerBase {
       
     IndexReader indexReader = req.getSearcher().getReader();
     Dictionary dictionary = new LuceneDictionary(indexReader, termSourceField);
+    spellChecker.clearIndex();
     spellChecker.indexDictionary(dictionary);
     reopen();
   }