As PHP documentations says mysqli and PDO do not return integers all the time.
I have checked and insertid from the other database drivers and they return integers.
Fix insertid() returned value.
I really wonder how much it takes to comment or merge such a simple pull request - one month so far.
Patience is a good thing :).
But I think the title makes it sound more confusing than it needs to be. Can you make it "Correct docblocks in mysqli and pdo."
It takes two clicks to merge it ... not too much.