I kinda love this tweet from Max Howell, and many of the replies it generated. I’ve never interviewed with Google (and I doubt they’d be interested in me) but I have gone on interviews where I was asked this kind of question. A question I could have answered, straight out of college, but that I’d be pretty fuzzy on, 20+ years later.
Of course, I’ve never written anything as cool or popular as Homebrew, so I do expect to have to prove myself a bit more than Mr Howell should have to. Which is one of the reasons why I occasionally work on Project Euler problems, or take an Algorithms course on Coursera.