Index: trunk/src/org/openstreetmap/josm/gui/dialogs/relation/RelationEditor.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/relation/RelationEditor.java	(revision 19401)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/relation/RelationEditor.java	(revision 19402)
@@ -153,6 +153,6 @@
     @Override
     public final boolean isDirtyRelation(boolean ignoreUninterestingTags) {
-        if (relation != null && relation.getDataSet() == null &&
-            relationSnapshot != null && relationSnapshot.getDataSet() == null) {
+        if (relation == null || relation.getDataSet() == null ||
+            relationSnapshot == null || relationSnapshot.getDataSet() == null) {
             return false;
         }