bug fix

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@15731 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/DescriptorExtensionList.java

@@ -131,7 +131,7 @@ public class DescriptorExtensionList<T extends Describable<T>, D extends Descrip
                 LOGGER.severe(d.getClass()+" doesn't extend Descriptor with a type parameter");
                 continue;   // skip this one
             }
-            if(Types.getTypeArgument(subTyping,0)==describableType)
+            if(Types.erasure(Types.getTypeArgument(subTyping,0))==(Class)describableType)
                 r.add(d);
         }
         return r;