Index: src/org/openstreetmap/josm/gui/dialogs/relation/RelationEditor.java
===================================================================
--- src/org/openstreetmap/josm/gui/dialogs/relation/RelationEditor.java	(revision 19431)
+++ src/org/openstreetmap/josm/gui/dialogs/relation/RelationEditor.java	(working copy)
@@ -152,12 +152,7 @@
 
     @Override
     public final boolean isDirtyRelation(boolean ignoreUninterestingTags) {
-        if (relation == null || relation.getDataSet() == null ||
-            relationSnapshot == null || relationSnapshot.getDataSet() == null) {
-            return false;
-        }
-
-        return !relation.hasEqualSemanticAttributes(relationSnapshot, ignoreUninterestingTags);
+        return relation != null && !relation.hasEqualSemanticAttributes(relationSnapshot, ignoreUninterestingTags);
     }
 
     /* ----------------------------------------------------------------------- */