ER_INVALID_CHARACTER_STRING and Incorrect information in frm file upon ALTERs on a table with virtual column

CREATE TABLE t1 (a INT, b INT, v INT AS (b));

--error ER_DUP_FIELDNAME

ALTER TABLE t1 CHANGE COLUMN IF EXISTS b a INT;

ALTER TABLE t1 FORCE;

# Cleanup

DROP TABLE t1;

mysqltest: At line 4: query 'ALTER TABLE t1 FORCE' failed: 1300: Invalid utf8mb4 character string: '\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5\xA5'

2018-05-15 16:02:56 139984398599936 [ERROR] mysqld: Incorrect information in file: './test/#sql-735a_4.frm'