During a backup/restore into new course I get a couple notices:

ERROR: invalid input syntax for integer:

SELECT * FROM mdl_quiz_categories WHERE course = '' AND stamp = 'mltest.wgtn.cat-it.co.nz+050811024546+1wCLMJ'

and then later on

Restoring quiz without user attempts. Restoring of user attempts will be implemented in Moodle 1.5.1

(but it's 1.5.2+ already!)