CE 1.9: native fallback system broken

Hi,
as stated here http://www.magentocommerce.com/knowledge-base/entry/ee114-ce19-rwd-dev-guide#changes-fallback, Magento CE 1.9 introduces parent/child theme configuration as explained by Alan Storm's article http://alanstorm.com/magento_parent_child_themes.

I think that the rewrite of Mage_Core_Model_Design_Package added in the RedLightBlinking_Setup module doesn't support this behavior.

I tried to install b-responsive on Magento CE 1.9 and have my default theme in my custom package to be a child of b-responsive itself and it didn't work. If I disable the RedLightBlinking_Setup module (so the rewrite) my theme works as expected and inherits from b-responsive.

How can we solve that? Should we add a version check in the rewrited model?