change curKmer/preKmer/nextKmer from deep copy to shallow copy
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/P4ForPathMergeVertex.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/P4ForPathMergeVertex.java
index 3b505fb..56fd837 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/P4ForPathMergeVertex.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/pathmerge/P4ForPathMergeVertex.java
@@ -129,7 +129,7 @@
             setStateAsNoMerge();
             
             // only PATH vertices are present. Find the ID's for my neighbors
-            curKmer.setAsCopy(getVertexId());  // TODO make a reference
+            curKmer = getVertexId();  // TODO make a reference
             
             curHead = isNodeRandomHead(curKmer);