The white supremacist who shot and killed 51 Muslims at two mosques in Christchurch, New Zealand, lost an attempt to undo his guilty pleas in a Court of Appeal ruling Thursday.AdvertisementThe panel of three judges dismissed Brenton Tarrant's claim that harsh prison conditions prompted him to make an involuntarily admission to terrorism, murder and attempted murder charges. His bid to withdraw his guilty pleas and seek a trial was "utterly devoid of merit," they wrote.AdvertisementThe Australian man, who is now 35, killed 51 worshippers and injured dozens more in March 2019 when he drove to two Christchurch mosques and opened...