复制课程图片出错

app/helpers/avatar_helper.rb

@@ -63,7 +63,7 @@ module AvatarHelper
     if source.class && source.id && File.exist?(disk_filename(source.class,source.id))
       avatar_image(source, false)
     elsif copy_course?(source.class, source.id)
-      avatar_image(source, true)
+      get_avatar(Course.find(source.is_copy)) rescue nil
     else
       File.join(relative_path,avatar_directory(source.class),'0')
     end