So you always have leaky roofs at your company? And if you don't like what he did, you just keep the repairs? Sorry for being picky, but you could've used "make a dog house" or something like that. I hope you don't put patches from interviewees in production code.
I should add that it's illegal, at least in California, to have somebody do productive work and not pay them. So if somebody is using work on a production system for an interview, you either must pay them for their time or you must throw away the code.
