China’s central bank governor on Sunday affirmed an official promise to avoid manipulating its currency to boost exports, an issue he said American and Chinese negotiators discussed in their latest talks aimed at ending a tariff war. Yi Gang gave no indication the two sides reached agreements beyond previous commitments produced by meetings of the Group of 20 major economies. He spoke at a news conference during the annual meeting of China’s ceremonial legislature. “We stress that we will never use the exchange rate for competitive purposes, nor will we use it to boost China’s exports,” Yi said. Yi took...