A root path on Unix is simply "/", but on Windows it's not so easy. There are for example "C:/" and "//host/dir". I'm sure that there are more cases, but here are a few that I found after a very quick look: 1. svn_path_canonicalize transforms "C:/" to "C:" which is not the same thing. 2. is_canonical does not understand that "C:/" is canonical. 3. svn_path_join does not get that if component is "C:/whatever", it is absolute. 4. svn_path_join_many does not get that if base is "C:/whatever", it is absolute.
Original issue reported by bliss