checking if a path exists

In vcstools, hg.py, checkout(), I had to disable this check:

if self.path_exists():
            sys.stderr.write("Error: cannot checkout into existing directory\n")
            return False


Obviously the solution is not to disable it, but it seems to me
path_exists() should return true for a temp path that was just
created.
I think this should also allow for empty folders;