spree/spree_product_groups — pull request #24 by stefansenk (2013-09-17 20:03:48+00:00)
Title: Chain scopes instead of merging in Spree::ProductScope#apply_on.

Product IDs passed in the scope were being overridden by the product group's product IDs during the merge. This change chains the scopes instead of merging them.
Fixes issue #11.