OTOH, it's not unreasonable to mandate that applicants have some specific free software contribution they can point to as an example. This shows several things. First, it shows that the person is geek enough to enjoy coding on their free time.
Actually, as an architect that is part of the interviewing team, I've found that the best programmers we've hired are people that do have outside interests. When they go to program, they bring the wealth of other experiences with them.
Not only that, but those who spend the majority of their time coding seem to lose social skills which make them a viable part of the team atmosphere we engender at work.