[anonymouz]

It's a trade off you make when you first choose the license: Either you leave the upgrade clause in, as recommended by the FSF. Then anyone can easily upgrade the license of the project to a new version of the GPL (or just use it as if it were licensed under the new version). The drawback is of course that you trust the FSF that new versions of the license match the spirit of the old ones, or that you find them at least agreeable.

Or you remove the upgrade clause. In that case you can be absolutely sure that nobody can sneak in new terms that you don't agree with. On the other hand, if you do actually want to change the license (e.g., upgrade to a new version of the GPL), you'll have to ask all the contributors to agree to the license change explicitly.