Jan 29 (Reuters) Sri Lanka's new govt will spell out populist measures to cut the cost of living when it unveils a supplementary budget today, but an absence of credible steps to boost revenue could hurt the island nation's fiscal consolidation. New administration of President Sirisena, which ended the decade-long rule of Mahinda Rajapaksa, has pledged to fix a "scary" economy plagued by what it calls faulty data