Index: trunk/src/org/openstreetmap/josm/tools/Geometry.java
===================================================================
--- trunk/src/org/openstreetmap/josm/tools/Geometry.java	(revision 19271)
+++ trunk/src/org/openstreetmap/josm/tools/Geometry.java	(revision 19272)
@@ -705,4 +705,5 @@
         inter.intersect(a2);
 
+        // Note: Area has an equals method that takes Area; it does _not_ override the Object.equals method.
         if (inter.isEmpty() || !checkIntersection(inter, eps)) {
             return new Pair<>(PolygonIntersection.OUTSIDE, inter);
@@ -1196,4 +1197,5 @@
                 for (PolyData outer : mp.getOuterPolygons()) {
                     if (!outer.isClosed()
+                            || !polygonArea.getBounds2D().contains(outer.getBounds())
                             || PolygonIntersection.FIRST_INSIDE_SECOND != polygonIntersection(getArea(outer.getNodes()),
                                     polygonArea)) {