fix a bug of tab2fasta
fix a bug of tab2fasta

shenwei356/bio_scripts,zctea/bio_scripts,shenwei356/bio_scripts,DawnEve/bio_scripts,DawnEve/bio_scripts,zctea/bio_scripts,DawnEve/bio_scripts,shenwei356/bio_scripts,DawnEve/bio_scripts,zctea/bio_scripts,zctea/bio_scripts,DawnEve/bio_scripts,shenwei356/bio_scripts,zctea/bio_scripts