Re-assign host access permission to MySQL user

The accepted answer only renamed the user but the privileges were left behind.

I'd recommend using:

RENAME USER 'foo'@'1.2.3.4' TO 'foo'@'1.2.3.5';

According to MySQL documentation:

RENAME USER causes the privileges held by the old user to be those held by the new user.

For reference, the solution is:

UPDATE mysql.user SET host = '10.0.0.%' WHERE host = 'internalfoo' AND user != 'root';
UPDATE mysql.db SET host = '10.0.0.%' WHERE host = 'internalfoo' AND user != 'root';
FLUSH PRIVILEGES;