Index: /trunk/src/org/openstreetmap/josm/data/osm/visitor/MergeVisitor.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/osm/visitor/MergeVisitor.java	(revision 1947)
+++ /trunk/src/org/openstreetmap/josm/data/osm/visitor/MergeVisitor.java	(revision 1948)
@@ -150,4 +150,13 @@
     }
 
+    protected void fixIncomplete(Way w) {
+        if (!w.incomplete)return;
+        if (w.incomplete && w.getNodesCount() == 0) return;
+        for (Node n: w.getNodes()) {
+            if (n.incomplete) return;
+        }
+        w.incomplete = false;
+    }
+
     /**
      * Postprocess the dataset and fix all merged references to point to the actual
@@ -157,4 +166,5 @@
         for (Way w : myDataSet.ways) {
             fixWay(w);
+            fixIncomplete(w);
         }
         for (Relation r : myDataSet.relations) {
@@ -243,5 +253,5 @@
                     //
                     conflicts.add(my,other);
-                } else if (my.incomplete) {
+                } else if (my.incomplete && !other.incomplete) {
                     // my is incomplete, other completes it
                     // => merge other onto my
@@ -249,4 +259,14 @@
                     my.incomplete = false;
                     my.cloneFrom(other);
+                    merged.put(other, my);
+                } else if (!my.incomplete && other.incomplete) {
+                    // my is complete and the other is incomplete
+                    // => keep mine, we have more information already
+                    //
+                    merged.put(other, my);
+                } else if (my.incomplete && other.incomplete) {
+                    // my and other are incomplete. Doesn't matter which one to
+                    // take. We take mine.
+                    //
                     merged.put(other, my);
                 } else if (my.deleted && ! other.deleted && my.version == other.version) {
Index: /trunk/test/unit/org/openstreetmap/josm/data/osm/visitor/MergeVisitorTest.java
===================================================================
--- /trunk/test/unit/org/openstreetmap/josm/data/osm/visitor/MergeVisitorTest.java	(revision 1947)
+++ /trunk/test/unit/org/openstreetmap/josm/data/osm/visitor/MergeVisitorTest.java	(revision 1948)
@@ -3,4 +3,5 @@
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -8,5 +9,7 @@
 import java.io.File;
 import java.text.MessageFormat;
+import java.util.Arrays;
 import java.util.Calendar;
+import java.util.Collections;
 import java.util.Date;
 import java.util.GregorianCalendar;
@@ -21,4 +24,5 @@
 import org.openstreetmap.josm.data.osm.DataSet;
 import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.data.osm.OsmPrimitive;
 import org.openstreetmap.josm.data.osm.Relation;
 import org.openstreetmap.josm.data.osm.RelationMember;
@@ -978,6 +982,121 @@
     }
 
-
-
-
+    /**
+     * Merge an incomplete way with two incomplete nodes into an empty dataset.
+     * 
+     * Use case: a way loaded with a multiget, i.e. GET /api/0.6/ways?ids=123456
+     */
+    @Test
+    public void newIncompleteWay() {
+        DataSet their = new DataSet();
+        their.version = "0.6";
+
+        Node n1 = new Node(1);
+        n1.version = 1;
+        n1.incomplete = true;
+        their.addPrimitive(n1);
+
+        Node n2 = new Node(2);
+        n2.version = 1;
+        n2.incomplete = true;
+        their.addPrimitive(n2);
+
+        Way w3 = new Way(3);
+        w3.incomplete = true;
+        w3.setNodes(Arrays.asList(n1,n2));
+        their.addPrimitive(w3);
+
+        DataSet my = new DataSet();
+        their.version = "0.6";
+
+        MergeVisitor visitor = new MergeVisitor(my,their);
+        visitor.merge();
+
+        assertEquals(0,visitor.getConflicts().size());
+
+        OsmPrimitive p= my.getPrimitiveById(1);
+        assertNotNull(p);
+        assertTrue(p.incomplete);
+        p= my.getPrimitiveById(2);
+        assertNotNull(p);
+        assertTrue(p.incomplete);
+        p= my.getPrimitiveById(3);
+        assertNotNull(p);
+        assertTrue(p.incomplete);
+
+        Way w = (Way)my.getPrimitiveById(3);
+        assertNotNull(w);
+        assertTrue(p.incomplete);
+        assertEquals(2, w.getNodesCount());
+        assertTrue(w.getNode(0).incomplete);
+        assertTrue(w.getNode(1).incomplete);
+    }
+
+    /**
+     * Merge an incomplete way with two incomplete nodes into a dataset where the way already exists as complete way.
+     * 
+     * Use case: a way loaded with a multiget, i.e. GET /api/0.6/ways?ids=123456 after a "Update selection " of this way
+     */
+    @Test
+    public void incompleteWayOntoCompleteWay() {
+        DataSet their = new DataSet();
+        their.version = "0.6";
+
+        Node n1 = new Node(1);
+        n1.version = 1;
+        n1.incomplete = true;
+        their.addPrimitive(n1);
+
+        Node n2 = new Node(2);
+        n2.version = 1;
+        n2.incomplete = true;
+        their.addPrimitive(n2);
+
+        Way w3 = new Way(3);
+        w3.incomplete = true;
+        w3.setNodes(Arrays.asList(n1,n2));
+        their.addPrimitive(w3);
+
+        DataSet my = new DataSet();
+        their.version = "0.6";
+
+        Node n4 = new Node(new LatLon(0,0));
+        n4.id = 1;
+        n4.version = 1;
+        n4.incomplete = false;
+        my.addPrimitive(n4);
+
+        Node n5 = new Node(new LatLon(1,1));
+        n5.id = 2;
+        n5.version = 1;
+        n5.incomplete = false;
+        my.addPrimitive(n5);
+
+        Way w6 = new Way(3);
+        w6.incomplete = false;
+        w6.setNodes(Arrays.asList(n4,n5));
+        my.addPrimitive(w6);
+
+        MergeVisitor visitor = new MergeVisitor(my,their);
+        visitor.merge();
+
+        assertEquals(0,visitor.getConflicts().size());
+
+        OsmPrimitive p= my.getPrimitiveById(1);
+        assertNotNull(p);
+        assertTrue(!p.incomplete);
+        p= my.getPrimitiveById(2);
+        assertNotNull(p);
+        assertTrue(!p.incomplete);
+        p= my.getPrimitiveById(3);
+        assertNotNull(p);
+        assertTrue(!p.incomplete);
+
+        Way w = (Way)my.getPrimitiveById(3);
+        assertNotNull(w);
+        assertTrue(!p.incomplete);
+        assertEquals(2, w.getNodesCount());
+        assertTrue(!w.getNode(0).incomplete);
+        assertTrue(!w.getNode(1).incomplete);
+    }
 }