Index: /trunk/src/org/openstreetmap/josm/data/osm/TagCollection.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/osm/TagCollection.java	(revision 14517)
+++ /trunk/src/org/openstreetmap/josm/data/osm/TagCollection.java	(revision 14518)
@@ -123,5 +123,4 @@
         if (primitives == null || primitives.isEmpty()) return tags;
         // initialize with the first
-        //
         tags.add(TagCollection.from(primitives.iterator().next()));
 
@@ -132,5 +131,7 @@
                 continue;
             }
-            tags.add(tags.intersect(TagCollection.from(primitive)));
+            tags = tags.intersect(TagCollection.from(primitive));
+            if (tags.isEmpty())
+                break;
         }
         return tags;
Index: /trunk/test/unit/org/openstreetmap/josm/data/osm/TagCollectionTest.java
===================================================================
--- /trunk/test/unit/org/openstreetmap/josm/data/osm/TagCollectionTest.java	(revision 14517)
+++ /trunk/test/unit/org/openstreetmap/josm/data/osm/TagCollectionTest.java	(revision 14518)
@@ -706,3 +706,21 @@
         assertEquals("0", f.getSummedValues("k"));
     }
+
+    /**
+     * Test method for {@link TagCollection#commonToAllPrimitives(Collection)}.
+     */
+    @Test
+    public void testCommonToAllPrimitives() {
+        Tagged t1 = new Node();
+        t1.put("k1", "10");
+        t1.put("k2", "20");
+        Tagged t2 = new Node();
+        t2.put("k2", "20");
+        TagCollection c = TagCollection.commonToAllPrimitives(Arrays.asList(t1, t2));
+        assertEquals(1, c.size());
+        assertFalse(c.hasValuesFor("k1"));
+        assertTrue(c.hasValuesFor("k2"));
+        assertEquals(1, c.getValues("k2").size());
+        assertEquals("20", c.getValues("k2").iterator().next());
+    }
 }