Attribute has wrong type in ALTER TABLE

Hi everyone,

the statements below result in an error "ERROR:  attribute 1 of type
t0 has wrong type":

CREATE TABLE t0(c0 VARCHAR(10));
INSERT INTO t0(c0) VALUES('');
ALTER TABLE t0 ALTER c0 SET DATA TYPE TEXT, ADD EXCLUDE (('a' LIKE
t0.c0) WITH =); -- unexpected: ERROR:  attribute 1 of type t0 has
wrong type

This is unexpected, since breaking up the ALTER TABLE actions does not
result in this error:

CREATE TABLE t0(c0 VARCHAR(10));
INSERT INTO t0(c0) VALUES('');
ALTER TABLE t0 ALTER c0 SET DATA TYPE TEXT;
ALTER TABLE t0 ADD EXCLUDE (('a' LIKE t0.c0) WITH =); -- no error

Best,
Manuel