Ethiopia’s prime minister said negotiations on Tuesday with Egypt and Sudan had paved the way for an agreement over the country’s hydroelectric dam on one of the Nile River’s tributaries, in a sign of progress in efforts to end a decadelong dispute over management of the river’s waters. Prime Minister Abiy Ahmed said talks convened by South Africa and the African Union and held over videoconference had resulted in a “major common understanding” toward an eventual deal, as he also acknowledged for the first time that the…