problem with migrations/schema loading when using STI

I ran into a problem when deploying a Rails3 app on a new server. I have a couple of STI models, and when running db:migrate or schema:load, AR would attempt to parse the associations in the STI models, based on tables that it hadn't yet created, and would fail. (I didn't notice it in development as the STI models were created after the table which they inherited from already existed.)

For example, I would get the following error, generated from an STI model:

# rake db:schema:load RAILS_ENV=production
PGError: ERROR:  relation "offers" does not exist
LINE 4:              WHERE a.attrelid = '"offers"'::regclass
                                        ^
:             SELECT a.attname, format_type(a.atttypid, a.atttypmod), d.adsrc, a.attnotnull
              FROM pg_attribute a LEFT JOIN pg_attrdef d
                ON a.attrelid = d.adrelid AND a.attnum = d.adnum
             WHERE a.attrelid = '"offers"'::regclass
               AND a.attnum > 0 AND NOT a.attisdropped
             ORDER BY a.attnum
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:202:in `rescue in log'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:194:in `log'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/postgresql_adapter.rb:483:in `query'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/postgresql_adapter.rb:1015:in `column_definitions'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/postgresql_adapter.rb:662:in `columns'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/base.rb:679:in `columns'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/base.rb:687:in `columns_hash'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/base.rb:780:in `descends_from_active_record?'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/base.rb:786:in `finder_needs_type_condition?'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/base.rb:897:in `relation'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/named_scope.rb:32:in `scoped'
/usr/local/lib/ruby/gems/1.9.1/gems/activerecord-3.0.0/lib/active_record/base.rb:441:in `where'
/data/app/works/app/models/work_offer.rb:5:in `<class:WorkOffer>'

Following is my work_offer.rb, AR was choking on the SQL being stored in a class variable:

class WorkOffer < Offer

  has_one :country, :through => :work

  default_scope where("work_id is not null and user_id is null")

  cattr_reader :joiners
  @@joiners = 'INNER JOIN "works" ON "works"."id" = "offers"."work_id" 
    left outer join "countries" on "works"."country_id" IS NOT NULL
    inner join "areas" on ("works"."country_id" = "countries"."id" 
    and "countries"."area_id" = "areas"."id")'
    # used for scopes because the activerecord joins doesn't do it

end

The workaround was to temporarily move the STI models out of my app/models folder, run db:schema:load, and then move them back.

Since STI models don't have their own schema, it seems that they should be skipped over when loading the schema?