fixed string index out of range exception#51

Goury wants to merge 1 commit intoellmetha:mainellmetha/django-precise-bbcode:mainfrom

Goury:bugfix/string-index-out-of-range-in-defaults/tag.pyGoury/django-precise-bbcode:bugfix/string-index-out-of-range-in-defaults/tag.pyCopy head branch name to clipboard