LONDON—A London judge on Wednesday widened the scope of a U.S. appeal against a block on the extradition of Wikileaks founder Julian Assange from Britain and will hear the renewed bid in late October. A judge ruled in January that Assange should not be extradited to the United States to face criminal charges including breaking a spying law, saying his mental health problems meant he would be at risk of suicide. Assange faces 18 criminal charges in the United States of breaking an espionage law and conspiring to hack government computers. WikiLeaks published a U.S. military video in 2010 showing a 2007 attack by Apache helicopters in Baghdad that killed a dozen people, including two Reuters news staff. It then released thousands of secret classified files and diplomatic cables. The legal saga began soon afterwards when Sweden sought Assange’s extradition from Britain over allegations of sex crimes. When he lost …