don't raise a chromosome discrepancy error for unmapped reads in BAM dbs.
don't raise a chromosome discrepancy error for unmapped reads in BAM dbs.

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