Rails 3.1 Assets are being fingerprinted in production but rendered HTML is not

Everything works great in Development. And app deploys as normal with Capistrano. Assets (javascript & css) appear to be fully pre-compiled and each, along with images, are given a "fingerprint". Problem is when using image_tag("image-name.png") in my view the html it creates in production doesn't include the 'fingerprint'.

The rendered HTML we get in production:

<img alt="Image-name" src="/assets/image-name.png" />

instead of, what I would expect, should be:

<img alt="Image-name" src="/assets/image-name-b89cae2830c2901f844c353b3f3942fe.png" />

So which of Rails 3.1's myriad config options did we botch?

Edit

The troublesome images appear to be those included in a 3rd-party Colorbox image viewing tool we use. Rails 3.1 is fingerprinting its assets (border.png, etc.) but, clearly, the source code for this javascript library doesn't use helpers like image_tag. So in production it is still looking for images named /assets/colorbox/开发者_如何学JAVAborder.png. Currently images are in /vendor/assets/images and work fine in Development. Is there a way to prevent just these images from being "fingerprinted"?

Well, here's how I hacked the 3rd-party files to make things work:

The offending images were in files like vendor/assets/stylesheets/colorbox.css. I first changed the extension of the files to .scss then I changed each url(colorbox/image.png) to image_url("color box/image.png") and now everything is peachy. Assets are served normally in development and fingerprinted in production.

Still like to see the "proper" way to add 3rd-party (vendor) javascript libraries & css to a Rails 3.1 app. Rails team must have anticipate a drop-in solution that doesn't require editing?!? So, please, feel free to offer up other solutions.

Aside: where I previously had manually configured my Capistrano recipe with:

run "cd #{release_path}; RAILS_ENV=production bundle exec rake assets:precompile"

…and its accompanying after deploy:update_code …. I have now removed those lines and instead added load 'deploy/assets to my Capfile. I don't think this makes any difference in the above problem but I wanted to document it anyway as adding your own recipe for pipeline precompiling is no longer necessary in Capistrano 2.8 as it was in the 3.1rc days.