Faceted navigation doesn't work properly with rating (timebound)

To reproduce, one example:

• On the GoGreen test server, on the English site, products section, there is a product with 5 stars ("Tamara's Ratatouille")
• Under "Refine your selection" choose "4 stars or more"
  Expected result: Results with 4 stars or more, including "Tamara's Ratatouille"
  Actual result: "Tamara's Ratatouille" is not there

• Now click "5 stars"
  Expected result: "Tamara's Ratatouille"
  Actual result: "Organic Cotton Reusable Lunch Bag", which has 4 stars