Am 2016-08-25 um 10:45 schrieb Gianfranco Costamagna:
I see many GPL-2 similar-looking licenses, with some special exceptions, e.g. "In addition to the above license, you can relicense this software in whatever form you want, with a special exception: you can't do foo and bar if you change the license"
The problem about additional GPL-2 clauses seems to be that they can be dropped at any time. An unpleasant contributor can do so any time and I would not be able to incorporate his changes if I wanna keep the additional freedoms I wanna guarantee for the upstream version.