Rails 3.1 SASS资产助手不包括RAILS_RELATIVE_URL_ROOT / relative_url_root

I have been working on an upgrade to Rails 3.1 from 2.3.11. One of the main hurdles to clear is the conversion to the asset pipeline. In this process I decided to convert my css to sass (scss). In rails 3.1 all assets delivered through the pipeline receive a hash appended to the filename in production. Because of this, all the images referenced in my css now needed to use the image-path or image-url helpers in sass. The issue is, that even though I have set my ENV['RAILS_RELATIVE_URL_ROOT'] in my environment.rb file sass asset helper fail to include the relative_url_root.I have been working on an upgrade to Rails 3.1