Initialize the OSTree for a release

def ostree_init(self, release):
        """Initialize the OSTree for a release"""
        out = release['output_dir'].rstrip('/')
        base = os.path.dirname(out)
        if not os.path.isdir(base):
            self.log.info('Creating %s', base)
            os.makedirs(base, mode=0755)
        if not os.path.isdir(out):
            self.mock_chroot(release, release['ostree_init'])