Fix empty alt allele bug. (#2456)
Fix empty alt allele bug. (#2456)


danking/hail,danking/hail,danking/hail,danking/hail,hail-is/hail,hail-is/hail,danking/hail,cseed/hail,hail-is/hail,cseed/hail,cseed/hail,hail-is/hail,cseed/hail,cseed/hail,danking/hail,hail-is/hail,cseed/hail,hail-is/hail,hail-is/hail,danking/hail,cseed/hail,danking/hail,hail-is/hail,cseed/hail