bugfix for null compare

see http://www.yacy-forum.de/viewtopic.php?p=16980#16980

git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@1644 6c8d7289-2bf4-0310-a012-ef5d649a1542

source/de/anomic/kelondro/kelondroTree.java

@@ -265,7 +265,7 @@ public class kelondroTree extends kelondroRecords implements kelondroIndex {
                         throw new kelondroException(filename, "kelondroTree.Search.process: thenode==null");
                     }
                     k = thenode.getKey();
-                    if ((k != null) & (visitedNodeKeys.contains(k))) {
+                    if ((k != null) && (visitedNodeKeys.contains(k))) {
                         // we have loops in the database.
                         // to fix this, all affected nodes must be patched
                         thenode.setOHByte(magic, (byte) 1);