construct_finder_sql and :select option

Currently, construct_finder_sql gives precedence to :select defined within the current scope over any passed in option. Unfortunately this breaks what I thought was a nice clean solution to finding what tags were applied to a model within a scope, e.g:

module Taggable

   def self.included(base)      base.class_eval do

       has_many :taggings, :as => :taggable, :dependent => :destroy        has_many :tags, :through => :taggings


       def self.tags          Tag.find_by_sql(construct_finder_sql(            :select => 'DISTINCT tags.*',            :joins => { :taggings => :tag }          ))        end

     end    end


This works find when not scoped but when scoped it breaks down, e.g:


produces the following sql:

   SELECT DISTINCT products.*    FROM `products`    INNER JOIN `manufacturers`      ON `manufacturers`.id = `products`.manufacturer_id    INNER JOIN `product_types`      ON `product_types`.id = `products`.product_type_id    INNER JOIN `taggings`      ON `taggings`.taggable_id = `products`.id      AND `taggings`.taggable_type = 'Product'    INNER JOIN `tags`      ON `tags`.id = `taggings`.tag_id    WHERE ((products.visible = 1      AND manufacturers.visible = 1      AND product_types.visible = 1)      AND (`products`.shop_id = 1))

Ticket #9861 in the Trac database tries to fix the problem for all options but runs into problems over whether to combine or overwrite options. I'd like to fix it just for :select - does anyone have any cases where the scoped :select option should win out over a passed in :select? Changing the order doesn't break any existing tests.