I believe that in order to do that, they would need to aggregate the copyright or get permission to change the license from each contributor. From what I unders

I believe that in order to do that, they would need to aggregate the copyright or get permission to change the license from each contributor. From what I understand, most projects that have dual-licensed have required contributor assignment of copyright from early on. Edit: Here's a good overview on it http://opensource.com/law/10/9/copyright-aggregation http://opensource.com/law/10/9/copyright-aggregation