fix rightmost read calculation
fix rightmost read calculation

tabbott/diagnose_dups,fw1121/diagnose_dups,genome/diagnose_dups,fw1121/diagnose_dups,tabbott/diagnose_dups,tabbott/diagnose_dups,tabbott/diagnose_dups,genome/diagnose_dups,fw1121/diagnose_dups,genome/diagnose_dups,fw1121/diagnose_dups,genome/diagnose_dups,genome/diagnose_dups,tabbott/diagnose_dups,fw1121/diagnose_dups,genome/diagnose_dups