SCSS precompile:assets throws invalid CSS due to http url in compiled asset file

Rails 3.1.22 sass-rails 3.2 - actionpack dependency prevents upgrading

rake assets:precompile throws error in a file called admin.css.scss

Here is the compile portion where it's complaining :

td .current{padding-right:12px;background-repeat:no-repeat;background-position:right center}
td .asc{background-image:url(http://ift.tt/1gupCBa)}
td .desc{background-image:url(http://ift.tt/1Ygf36T)}
#overlay{background:url(http://ift.tt/1gupzVS) 

I have these files in production right now, but the last time I precompiled was probably 6+ months ago - at that time I still had the CDN in effect and can't figure out what's different.

I've tried variations before coming to SO - image-url, image-path, asset-url, asset-path, tried changing scss to css.erb and using the <%= asset_path () %> helper, I keep getting this error. The actual error is :

Sass::SyntaxError: Invalid CSS after " http": expected ";", was "://cdn2.mysite..."

Does anyone have any idea how I can resolve this syntax error?