[FIXED HUDSON-2991] show more compact error msg for missing help

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@27239 71c3de6d-444a-0410-be80-ed276b4c234a

war/resources/scripts/hudson-behavior.js

@@ -469,8 +469,11 @@ var hudsonRules = {
                 // make it visible
                 new Ajax.Request(this.getAttribute("helpURL"), {
                     method : 'get',
-                    onComplete : function(x) {
+                    onSuccess : function(x) {
                         div.innerHTML = x.responseText;
+                    },
+                    onFailure : function(x) {
+                        div.innerHTML = "<b>ERROR</b>: Failed to load help file: " + x.statusText;
                     }
                 });
             } else {