SOLR-1695: Added an earlier check for multiple values being used in the uniqueKey field - prior to this the only check was done in the UpdateHandler (IndexSchema logs an erro if the field is declared multiValued=true, but it's not considered fatal since it will still work as long as clients only send one value)
lucene/solr/trunk/CHANGES.txt
lucene/solr/trunk/src/java/org/apache/solr/update/DocumentBuilder.java