Remove obsolete line.

This code is broken (it should say association_scope.uniq_value rather
than options[:uniq]) but the tests still pass.

I think it is designed to uniq-ify associations using finder_sql.
However, I am about to remove that anyway.

activerecord/lib/active_record/associations/collection_association.rb

@@ -383,7 +383,6 @@ module ActiveRecord
               scoped.all
             end
 
-          records = options[:uniq] ? uniq(records) : records
           records.each { |record| set_inverse_instance(record) }
           records
         end