Alex wrote: The proviso above is definitely not GPL-compatible, so in that sense the poster is correct (I would say it's an extra restriction to the GPL). I *suspect* some might even treat it as a non-free licence - for example, the QPL does roughly what you want (#3.b) and although the FSF consider it a free licence, others don't.
I think you might be referring to debian? Well, there are a few nasties in how the QPL interacts with some contract law and there's the ability of the copyright holder to make licensees spend a lot of money defending themselves in court, but fortunately most use of the QPL is scuppered by misapplication of it or other practical problems. There's also a strong argument for dual licensing, which is what QPL author Trolltech