fixed charset detection with wrong regexp.

I asume that you try to find the standard «# -*- coding: utf-8 -*-» expression at the start of the readed file, but you simply use the wrong regexp since you happily re-search with _line_re instead of _coding_re.

with django, I have a file that start with «try:» and it don't break at 

        try:
            codecs.lookup(charset)
        except LookupError:
            charset = 'utf-8'

. so the declared charset become «try:»...