> The very short agreement basically just made it explicit that they are not responsible of a contributor submitting code they don't own copyright to
This is often times called a "DCO" — Developer Certificate of Origin. I think that is a better name for these, as the term "CLA" is very much associated with the controversial copyright reassignment/relicensing clauses.
> Has anyone seen GPL+CLA in the wild?
Does FSF copyright assignment count? They do that on many of their projects (including Emacs).
Mono used to have a CLA to Novell. There were GPL and LGPL parts. It turned out to be beneficial because it enabled Xamarin (made up of mono developers) to acquire licensing rights to redistribute and relicense it after Novell dropped support for the project.
> This is not the case of all open source licenses. And that is fine. Don't assume all my work has to be part of your crusade.
Indeed, I've contributed to one open source project with a CLA, it had an Apache v2 license... So It didn't really seem to make any practical difference to that license. The very short agreement basically just made it explicit that they are not responsible of a contributor submitting code they don't own copyright to - which seems a little overly defensive but fair enough as Apache doesn't explicitly protect against that.
That said, I don't like the barrier CLAs impose on open source projects. Has anyone seen GPL+CLA in the wild?