A Kenyan-made film on lesbian love will break new ground when it premieres at the Cannes festival this week — but at home, the movie has been banned, a decision exposing the often bitter debate over homosexuality in East Africa. “Rafiki” –- meaning “friend” in Kiswahili –- is adapted from a prize-winning short story called “Jambula Tree” by Ugandan writer Monica Arac de Nyeko. The film, telling the tale of two young women whose fathers are political rivals, is the first-ever film from Kenya to get a slot at the world’s most prestigious cinema festival. It premieres on Wednesday in the “Un Certain Regard” category, reserved for emerging directors or unexpected or marginal themes. The ban was announced by Ezekiel Mutua, a self-described “fervent moral crusader” who runs the Kenya Film Classification Board and has described his job as “upholding our cultural and moral values through content regulation.”