Earlier quoted context omitted.
I'm not sure that you fully read the parent comment. I could care less about their Subversion expertise. My company doesn't even use Subversion anywhere. However, if you list " 10 years experience with " on your resume, then you should absolutely be prepared to discuss your experience with at a high level. Not anal minutia or contrived trick questions, but certainly you should be able to respond to an open-ended ques…
There is no less productive form of interview than the "resume validation interview". Resumes are practically useless in the best case. Here, you seem to propose paying a premium for candidates who can properly estimate their facility with VCS systems and then cogently discuss that estimation in an interview . That can't possibly be a skill relevant to building software on your team!
I think that's an unfair interpretation of what StevePerkins is saying.
I don't get the impression from him that VCS knowledge in particular will make-or-break a candidate. He's saying that IF the candidate put it on his resume, then the candidate himself is the one who opened that door for discussion.
Out of the infinite list of programming topics to discuss, what are some options to narrow it down? Well, the candidate (through his own volition) put on his resume... so... let's talk about Topic X! It doesn't matter what Topic X happens to be (whether it's "svn", "parallel algorithms", "Ruby", "TDD", "cloud scaling", whatever). What matters is that the candidate is the one who thought it important enough to highlight it. From there, it's reasonable to think it's something the candidate is already comfortable with discussing in depth. If not, he shouldn't put it on the resume.
Your response makes it seem like StevePerkins is playing Alex Trebek with Jeopardy random topics and asking "gotcha" questions. It's not random -- the source is the candidate's resume. It certainly seems fair and reasonable to discuss any topics the candidate put on his resume. Imo, it's also fair to augment with questions that are not represented on his resume (but that's a different discussion from StevePerkin's example.)