Difference in generators between test unit and rspec

All,

I am working on getting factory_girl_rails to automatically configure
itself as the fixture replacement when it is included in a project.

I am seeing some strange behavior differences with the generators
between test unit and rspec.

When I run 'rails generate model User name:string' with only test unit
configured, I get the following output:

Method orm
      Args [:active_record, {:migration=>true, :timestamps=>true}]
      Method test_framework
      Args [:test_unit, {:fixture=>true, :fixture_replacement=>nil}]
      Method integration_tool
      Args [:test_unit]
      Method performance_tool
      Args [:test_unit]
      Method fixture_replacement
      Args [:factory_girl]
            invoke active_record
            create db/migrate/20110907224210_create_users.rb
            create app/models/user.rb
            invoke test_unit
            create test/unit/user_test.rb
            create test/fixtures/users.yml

When I run the same command with rspec-rails installed, I get the
following output:

Method orm
      Args [:active_record, {:migration=>true, :timestamps=>true}]
      Method test_framework
      Args [:test_unit, {:fixture=>true, :fixture_replacement=>nil}]
      Method integration_tool
      Args [:test_unit]
      Method performance_tool
      Args [:test_unit]
      Method fixture_replacement
      Args [:factory_girl]
      Method integration_tool
      Args [:rspec]
      Method test_framework
      Args [:rspec]
            invoke active_record
            create db/migrate/20110907224326_create_users.rb
            create app/models/user.rb
            invoke rspec
            create spec/models/user_spec.rb
            invoke factory_girl
            create test/factories/users.rb

I can't seem to figure out why RSpec seems to respect the
fixture_replacement setting set to :factory_girl but test unit does
not.

I have quickly poured over the generator code and can't seem to find
where the disconnect is happening. I plan on spending some more time
tomorrow looking into this but thought I'd throw out a help in case
someone more familiar with the generator hooks might have an idea.

Thanks,
Mike