I think github makes a good crack at it
http://github.com/rortian/Retinex/blob/53a2f818ce301f4912b02...
But, you're right I was wrong to say anything about REST. I just thought it was an interest way to do a git tree explorer.
I'm sure it's not desirable to come up with a minimal character URL for this sort of thing, but I hard to see either approach as suboptimal.