config/initializers/compass.rb
# http://devcenter.heroku.com/articles/using-compass
require 'fileutils'
FileUtils.mkdir_p(Rails.root.join("tmp", "stylesheets"))
# Workaround Compass bug
module Compass::SassExtensions::Functions::Sprites
def sprite_path(map)
Sass::Script::String.new(map.filename)
end
Sass::Script::Functions.declare :sprite_path, [:map]
end