I realized this months ago when adding `updated_at` changes to the
other actions around here, and I just forgot this one, and I've had a
sticky on my desk about it since then! Finally done!
Before this change, clicking "I own this" or "I want this" on the item
page, while you own/want the item and it's in a specific list, would
remove the item from the list but *not* update the list's `updated_at`
timestamp. Now, it does!
This affects caching on main DTI, which relies on the list's
`updated_at` to decide when to render new HTML.
Emi Matchu
37bac38973