Martin> I don't think any change is necessary. os.path.commonprefix Martin> works just fine on path components: ...
>>> os.path.commonprefix(["/export/home", "/etc/passwd"]) '/e'
I suppose that's correct given the defined behavior of the function, but it certainly doesn't seem to be very path-like to me.
Martin> Of course, using it that way would require a library function Martin> that reliably splits a path into components; I think one would Martin> have to do abspath on arbitrary inputs.
See http://bugs.python.org/issue4755 for what I think is a function with more predictable behavior given that we are discussing paths and not just strings.