Remove ref to 404 test, do not discard tags from empty tags

js/id/graph/history.js

@@ -134,9 +134,13 @@ iD.History = function(context) {
             var difference = history.difference();
 
             function discardTags(entity) {
-                return entity.update({
-                    tags: _.omit(entity.tags, iD.data.discarded)
-                });
+                if (_.isEmpty(entity.tags)) {
+                    return entity;
+                } else {
+                    return entity.update({
+                        tags: _.omit(entity.tags, iD.data.discarded)
+                    });
+                }
             }
 
             return {

test/index.html

@@ -159,7 +159,6 @@
     <script src="spec/actions/noop.js"></script>
     <script src="spec/actions/reverse.js"></script>
     <script src="spec/actions/split.js"></script>
-    <script src="spec/actions/deprecate_tags.js"></script>
 
     <script src="spec/geo/extent.js"></script>