'Logs user in
- extended to understand session.s3.roles'

def login_bare(self, username, password):

    settings = self.settings
    utable = settings.table_user
    userfield = settings.login_userfield
    passfield = settings.password_field
    query = (utable[userfield] == username)
    user = current.db(query).select(limitby=(0, 1)).first()
    password = utable[passfield].validate(password)[0]
    if user:
        if ((not user.registration_key) and (user[passfield] == password)):
            user = Storage(utable._filter_fields(user, id=True))
            current.session.auth = Storage(user=user, last_visit=current.request.now, expiration=settings.expiration)
            self.user = user
            self.s3_set_roles()
            return user
    return False
