test if we can :read_group the group, not the namespace

app/controllers/namespaces_controller.rb

@@ -14,7 +14,7 @@ class NamespacesController < ApplicationController
 
     if user
       redirect_to user_path(user)
-    elsif group && can?(current_user, :read_group, namespace)
+    elsif group && can?(current_user, :read_group, group)
       redirect_to group_path(group)
     elsif current_user.nil?
       authenticate_user!