REPEAT(x,-1) returns a wrong data type

CREATE OR REPLACE TABLE t1 (i BIGINT);

INSERT INTO t1 VALUES (42);

CREATE OR REPLACE TABLE t2 AS SELECT

  REPEAT(i,0) AS c0,

  REPEAT(i,-1) AS c1

FROM t1;

SHOW CREATE TABLE t2;

+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------+

| Table | Create Table                                                                                                                                               |

+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------+

| t2    | CREATE TABLE `t2` (

  `c0` char(0) CHARACTER SET utf8 DEFAULT NULL,

  `c1` longtext CHARACTER SET utf8 DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------+