Изменения вступят в силу в версии Python 3.8. Термины master и slave будут заменены на parent/main/server («родитель»/«главный»/ «исполнитель») и child/worker («ребенок»/«работник»).
UPDATE
Thanks to
In 2003, the County of Los Angeles in California asked that manufacturers, suppliers and contractors stop using "master" and "slave" terminology on products; the county made this request "based on the cultural diversity and sensitivity of Los Angeles County".[17][18] Following outcries about the request, the County of Los Angeles issued a statement saying that the decision was "nothing more than a request".[17] Following the controversy, Global Language Monitor selected the term "master/slave" as the most politically incorrect word of 2004
Остальное было подытожено в следующем комменте
У всего мира крыша отъезжает. Тихо шурша