[t:3875], fix another bug

git-svn-id: file:///svn/mysql/tokudb-engine/tokudb-engine@33999 c7de825b-a66e-492c-adef-691d508d4ae1

storage/tokudb/ha_tokudb.cc

@@ -4798,6 +4798,7 @@ int ha_tokudb::read_data_from_range_query_buff(uchar* buf, bool need_val) {
     // if this is a covering index, this is all we need
     if (this->key_read) {
         assert(!need_val);
+        extract_hidden_primary_key(active_index, &curr_key);
         read_key_only(buf, active_index, &curr_key);
         error = 0;
     }