People say "No I don't have any past hobby work, never contributed to OSS, and all my professional work is verboten to show" that's not unusual, but it's also not an encouraging sign to me when interviewing.
Every time I find some open source I would contribute to, what I wanted to implement is already there or is already in the works. I'm not going to change shit just to change it. I'll buy them a coffee tip and leave.