[O] redefined-warning when applying org-hack to preserve headings when archiving

[Karl Voit]

Hi!

I applied Matt's http://orgmode.org/worg/org-hacks.html#sec-1-7-1 to
preserve top level headings when archiving to a file.

However, when I do archive headings, I get a "ad-handle-definition:
`org-archive-subtree' got redefined" warning which I have to look at
a couple of seconds before it finishes.

How can I prevent this from blocking my time?

Thanks!