'Sign the original file (`file_path`) with reviewer certs, then move
the signed file to the reviewers-specific signed path
(`reviewer_signed_file_path`) on private storage.'

def reviewer_sign_file(self):

    if (not self.extension.uuid):
        raise SigningError('Need    uuid    to    be    set    to    sign')
    if (not self.pk):
        raise SigningError('Need    version    pk    to    be    set    to    sign')
    ids = json.dumps({'id': self.review_id, 'version': self.pk})
    with statsd.timer('extensions.sign_reviewer'):
        try:
            sign_app(private_storage.open(self.file_path), self.reviewer_signed_file_path, ids, reviewer=True)
        except SigningError:
            log.info(('[ExtensionVersion:%s]    Reviewer    Signing    failed' % self.pk))
            if private_storage.exists(self.reviewer_signed_file_path):
                private_storage.delete(self.reviewer_signed_file_path)
            raise
