Fix infinite extension change (fix #528)
Fix infinite extension change (fix #528)

YoukaiCat/imgbrd-grabber,Bionus/imgbrd-grabber,Bionus/imgbrd-grabber,Bionus/imgbrd-grabber,Bionus/imgbrd-grabber,YoukaiCat/imgbrd-grabber,Bionus/imgbrd-grabber,Bionus/imgbrd-grabber