If I forgot to build an image with "--manifest", but I wanted to, I don't have a way to a fix that without rebuilding or pushing the image to a temporary location, removing the local copy, and creating the list with a reference to that remote copy.

I'd like to be able to "manifest create --amend" a list in place of a non-list, implicitly adding that now-unnamed non-list to the new list, or converting that non-list's image record into one that looks like was originally pulled from a list.