Alter table .. Add .. Primary Key fails with Column not found when columnName contains localized characters - w/a available

Database created with territory=es_MX and table with colunName Excepci≤n (taken from exception text for "ERROR XJ001: Excepci≤n de Java:...") trying to specify the column as the primary key using alter table fails:

Db Creation URL: connect 'jdbc:derby:toursMx;create=true;territory=es_MX';
– Create table
Create table Ciudad_de_Mexico2
( nombre varchar(24),
estado varchar(24),
Excepci≤n int );
– Create PK
ALTER TABLE Ciudad_de_Mexico2
ADD CONSTRAINT Mx_PK2 Primary Key (
Excepci≤n);
– ERROR 42831: 'EXCEPCI╙N' no puede ser una columna de clave primaria o clave - nica porque puede contener valores nulos.

– WORKAROUND: create the primary key when the table is created:

Create table Ciudad_de_Mexico
( nombre varchar(24),
estado varchar(24),
Excepci≤n int constraint mx_pk Primary Key);