Fixing query_pre for delta index - need to override the core index's …

…version, else nothing in delta index

lib/thinking_sphinx/index.rb

@@ -78,6 +78,7 @@ def to_config(index, database_conf, charset_type)
 
 source #{model.name.downcase}_#{index}_delta : #{model.name.downcase}_#{index}_core
 {
+sql_query_pre    = 
 sql_query        = #{to_sql(:delta => true).gsub(/\n/, ' ')}
 sql_query_range  = #{to_sql_query_range :delta => true}
 }