ref_file can't be const when gathering CRAM_REFERENCE
ref_file can't be const when gathering CRAM_REFERENCE

arq5x/bedtools2,jmarshall/bedtools2,arq5x/bedtools2,arq5x/bedtools2,jmarshall/bedtools2,arq5x/bedtools2,jmarshall/bedtools2,jmarshall/bedtools2,jmarshall/bedtools2,arq5x/bedtools2