Oops, that was sloppy. This Diagram was still from the time when it was needed to embed additional JavaScript on the page to handle the special promotion rules, (the current version would support this kind of promotion as a standard feature through the morph parameter), and I had just copied that from another variant. But that code just tested whether it was reaching 1st or 8th rank without considering the color, as Pawns cannot usually reach their own back rank...
Oops, that was sloppy. This Diagram was still from the time when it was needed to embed additional JavaScript on the page to handle the special promotion rules, (the current version would support this kind of promotion as a standard feature through the morph parameter), and I had just copied that from another variant. But that code just tested whether it was reaching 1st or 8th rank without considering the color, as Pawns cannot usually reach their own back rank...
Should be fixed now.