ALTER TABLE region MODIFY COLUMN r_comment varchar(152) CHARACTER SET utf8;
ERROR 1815 (HY000): Internal error: CAL0001: Alter table Failed: Altertable: Error in the action type

ALTER TABLE region MODIFY COLUMN r_comment varchar(152) COLLATE latin1_bin;
ERROR 1815 (HY000): Internal error: CAL0001: Alter table Failed: Altertable: Error in the action type

Realize that changing character set my change the max length of the column, since various character sets use different byte counts.

This should be done after or in conjunction with MCOL-130 ALTER TABLE does not support changing data type