The kernel's code of conduct, one week later

As far as I can tell from brief research, it's an obscure derogatory term with similar meaning to "SJW" or "feminist", occasionally used in such upstanding places as 4chan, referring to a stereotypical young woman with purple hair and a Tumblr account and socially liberal views. It's hard to trace the etymology but I guess the connection might have been reinforced by Vice Admiral Holdo in The Last Jedi (which upset many people because it has competent women in it). And in this specific case the primary author of the Contributor Covenant sometimes has purple hair, so the term has some literal accuracy. It's still incredibly stupid though.