middleware: external links open in new window

class ExtlinksBlankMiddleware(object):
    '''
    Makes sure all external and only exernal links open in a new window.
    '''
    def __init__(self):
        self.targets = re.compile(r'''target=.\w*.''')
        self.extlinks = re.compile(r'''<a (?P<old>[^>]*http.?://)''')
    def process_response(self, request, response):
        if ("text" in response['Content-Type']):
            response.content = self.targets.sub('', response.content)
            response.content = self.extlinks.sub('<a target="_blank" \g<old>',response.content)
            return response
        else:
            return response