The United Nations said Sunday that negotiations between Yemen’s warring sides to extend a nationwide cease-fire will continue, after an agreement was not reached before a deadline on October 2. In a statement, the UN’s envoy to Yemen called on all sides to refrain from acts of provocation as the talks continue. The development dampens hopes that the 6-month-old ceasefire could turn into a longer peace. The truce, which initially took effect in April, is the longest lull of fighting in Yemen’s civil war, now in its eighth year. The devastating conflict began in 2014, when the Iranian-backed Ho…