Crash in dynamic column API

static int test_mdev_4994(MYSQL *mysql)

{

  DYNAMIC_COLUMN dyncol;

  uint key= 1;

  DYNAMIC_COLUMN_VALUE val;

  int rc;

  val.type= MYSQL_TYPE_NULL;

  mariadb_dyncol_init(&dyncol); /* see patch for MDEV-4993 */

  rc= mariadb_dyncol_create_many_named(&dyncol, 1,&key, &val, 0);  /* crash */

  FAIL_IF(rc < 0, "Unexpected error");

  return OK;

}