InnoDB indexes are inconsistent with what defined in .frm for table after rebuilding table with index on blob

--source include/have_innodb.inc

CREATE TABLE t1 (b BLOB) ENGINE=InnoDB;

ALTER TABLE t1 ADD INDEX(b);

ALTER TABLE t1 FORCE;

# Cleanup

DROP TABLE t1;

2019-02-24  3:24:53 9 [ERROR] Found index b whose column info does not match that of MariaDB.

2019-02-24  3:24:53 9 [ERROR] InnoDB indexes are inconsistent with what defined in .frm for table ./test/t1

^ Found warnings in /dev/shm/var/log/mysqld.1.err