MySQL, Error 1175 when executing an UPDATE using a JOIN and including the PK in the WHERE clause

Question

Before I start I know that this can be solved by first executing the query.

SET SQL_SAFE_UPDATES = 0;

However, I am wanting to perform the update without having to first change the database's configuration every time.

I am attempting to update the table:

CREATE TABLE `nested_category` (
`category_id` INT AUTO_INCREMENT PRIMARY KEY,
`name` VARCHAR(20) NOT NULL,
`lft` INT NOT NULL,
`rgt` INT NOT NULL
);

Using the query:

UPDATE `nested_category` AS ns1
INNER JOIN `nested_category` AS ns2
ON (ns1.`lft` >= ns2.`rgt` OR ns1.`rgt` > ns2.`rgt`)
SET ns1.`rgt` = ns1.`rgt` +2,
    ns1.`lft` = ns1.`lft` +2
WHERE ns1.`category_id` = @sumID;

Does anyone know why I cannot perform this, and/or how I can perform it without having up change database settings?