Index: src/org/python/core/MergeState.java
===================================================================
--- src/org/python/core/MergeState.java	(revision 4524)
+++ src/org/python/core/MergeState.java	(working copy)
@@ -207,8 +207,11 @@
 
         this.kvdata[dest++] = this.kvdata[pb++];
         --nb;
-        if (nb == 0)
-            return;
+        if (nb == 0) {
+        	if (na != 0)
+                System.arraycopy(this.a, pa, this.kvdata, dest, na);
+        	return;
+        }
         if (na == 1) {
             // CopyB;
             System.arraycopy(this.kvdata, pb, this.kvdata, dest, nb);
@@ -332,8 +335,12 @@
 
         this.kvdata[dest--] = this.kvdata[pa--];
         --na;
-        if (na == 0)
-            return;
+        if (na == 0) {
+        	if (nb != 0)
+                System.arraycopy(this.a, 0, this.kvdata, dest-(nb-1), nb);
+        	return;
+        }
+
         if (nb == 1) {
             // CopyA;
             dest -= na;