Fix issues with identifying max fields for a tuple index when input file contains empty elements
Fix issues with identifying max fields for a tuple index when input file contains empty elements

bioinformed/pysam,bioinformed/pysam,pysam-developers/pysam,TyberiusPrime/pysam,mattions/pysam,mattions/pysam,daler/pysam,mattions/pysam,TyberiusPrime/pysam,nlhepler/pysam,dannon/pysam,TyberiusPrime/pysam,dannon/pysam,nlhepler/pysam,nlhepler/pysam,mattions/pysam,kyleabeauchamp/pysam,bioinformed/pysam,kyleabeauchamp/pysam,brendanofallon/pysam,bioinformed/pysam,carolinux/pysam,pysam-developers/pysam,daler/pysam,dannon/pysam,dannon/pysam,pysam-developers/pysam,dannon/pysam,kyleabeauchamp/pysam,brendanofallon/pysam,TyberiusPrime/pysam,kyleabeauchamp/pysam,kyleabeauchamp/pysam,brendanofallon/pysam,daler/pysam,daler/pysam,mattions/pysam,carolinux/pysam,carolinux/pysam,carolinux/pysam,nlhepler/pysam,daler/pysam,TyberiusPrime/pysam,nlhepler/pysam,pysam-developers/pysam,bioinformed/pysam,brendanofallon/pysam,brendanofallon/pysam,carolinux/pysam