On the other hand, I can't imagine someone with tons of OSS contributions who _isn't_ passionate about programming at some level.
However if we get a more competent candidate who likes gardening more than programming, we'll absolutely choose them over the pure passion person because they'll do the job better. They just have to show that competence in some other way, e.g. via the interviews or past job accomplishments.
Because excitement in any form is contagious, and I'd rather work alongside someone who is excited about something than someone who is not.
As an employee, I will burn out much faster in an environment where no one wants to be there than an environment where people share their curiosities and passions, even if they are not immediately work related.