X.org server I think was the one that had to be abandoned, or was it XFree86.. one of the major X11 implementations had to be completely abandoned and rewritten as whatever replaced it.
@freemo that didn't have anything to do with copyleft.
It literally did, though as pointed out by another commenter it didnt require a complete rewrite only partial, but did require a complet reorg and rename.
Here is a quote from wikipedia basically agreeing with what I said word for word.
> The newer terms are referred to as the XFree86 License 1.1. Many projects relying on XFree86 found the new license unacceptable, and the Free Software Foundation considers it incompatible with the version 2 of the GNU General Public License, though compatible with version 3.
That is correct, it is the other copyleft licenses in the eco system whose viral nature and incompatibility with the clause that caused the issue.