Ticket #4622: 4622.patch

_source/plugins/undo/plugin.js

@@ -390 +390 @@
 
                         this.index = image.index;
 
-                        this.currentImage = image;
+                        // Update current image with the actual editor
+                        // content, since actualy content may differ from
+                        // the original snapshot due to dom change. (#4622) 
+                        this.snapshots.splice( this.index, 1, ( this.currentImage =  new Image( this.editor ) ) );
 
                         this.fireChange();
                 },