I was searching for Subversion web frontends and found this StackOverflow answer. Some of the comments were exactly what you’d expect.
Why the hell would you like to check in/check out files through a web interface (if I understand well your question)?
Why the hell indeed! Fire and brimstone and a use case I don’t have sufficient empathy to understand!
It sounds like could use any regular VCS (judging by your edit) - why does it have to be web-based? Why do you want to check files in/out via the web?
Oh for Pete’s sake. Merlin Mann responds with such questions by asking why he’s not a potted fern; I think we should all adopt that.
Update: Turns out, I wrote about this back in 2013.