don't active unless it's run from tests

test/src/main/java/org/jvnet/hudson/test/TestExtensionLoader.java

@@ -52,6 +52,8 @@ public class TestExtensionLoader extends ExtensionFinder {
 
         List<ExtensionComponent<T>> result = new ArrayList<ExtensionComponent<T>>();
 
+        if (env==null)  return result;  // not in a test
+
         ClassLoader cl = hudson.getPluginManager().uberClassLoader;
         for (IndexItem<TestExtension,Object> item : Index.load(TestExtension.class, Object.class, cl)) {
             try {