[hail] store contig as index in densify (#6967)
[hail] store contig as index in densify (#6967)


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