Great, never had time to find out by myself how to do that. BTW: I had to remove vendor/assets path from line 5 because it doesn't exist in my repo, and git returns an error if path does not exist in repo.
You also probably should check for Gemfile.lock, as some assets are provided by gems.
This will fail on the first deploy because current_revision is not yet defined and the command capistrano uses to find current_revision will fail. You can add :on_error => :continue to the task definition and it won't fail, but it will skip it and you'll have to deploy twice on the first go in order to build you assets, which is still kind of hacky.
:on_error => :continue
Simple workaround for first deploy:
Hi all, is it essential to add lib/*/app/assets to my own list of locations to git log? Currently I have some gems downloaded, located under the /lib directory, and I sometimes need to edit their assets.