legion: fix for leaked reductions instances with emtpy equivalence sets
legion: fix for leaked reductions instances with emtpy equivalence sets

StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion