persistent-mysql migration: BLOB/TEXT column ... can't have a default value

when I start my application (for the first time, so it tries to migrate an existing DB), I get

Migrating: ALTER TABLE `aufgabe` ALTER COLUMN `Name` DROP DEFAULT
autotool-yesod: ConnectionError {errFunction = "query", errNumber = 1101, errMessage = "BLOB/TEXT column 'Name' can't have a default value"}

When I run this command in the DB directly:

MariaDB [____test]> ALTER TABLE `aufgabe` ALTER COLUMN `Name` DROP DEFAULT;
ERROR 1101 (42000): BLOB/TEXT column 'Name' can't have a default value

This also happens with mysql server version 5.5.49.

The fix would be to just not run this ALTER TABLE query? Indeed, to not create it? Because the DEFAULT is not there in the first place, so there's no reason to DROP it:

mysql> show create table aufgabe;
CREATE TABLE `aufgabe` (
  `ANr` int(11) NOT NULL AUTO_INCREMENT,
  `Name` text CHARACTER SET utf8 NOT NULL,
...

No file or test is named. Start by locating the persistent-mysql migration code that emits the reported ALTER TABLE query, reproduce it against the stated MySQL/MariaDB setup, and verify that migrations no longer fail when dropping a default from the BLOB/TEXT column.