1.486 special for a week.

core/src/main/java/hudson/Functions.java

@@ -1537,4 +1537,12 @@ public class Functions {
         DecimalFormat format = new DecimalFormat("##.00");
         return format.format(number) + " " + measure;
     }
+
+    /**
+     * 1.486 special
+     */
+    public static String getBackgroundImage() {
+        // for one week.
+        return System.currentTimeMillis() < 1350696100409L ? "i486.jpg" : "jenkins.png";
+    }
 }