journal: don't show "error" popup when navigating away from page while lazy info is loading

The "error" box would pop up in the Journal view when quickly pointing and
clicking a link while the info was loading.

This fix might prevent showing valid error messages in some browsers.

rhodecode/public/js/rhodecode.js

@@ -425,7 +425,9 b' var ajaxGET = function(url,success) {'
     var callback = {
         success: success,
         failure: function (o) {
-            alert("error");
+            if (o.status != 0) {
+                alert("error: " + o.statusText);
+            };
         },
     };