Patch for bug http://bugs.python.org/issue1293

The patch doesn't do the whole name mangling mambo jambo on purpose. MS sure does some weird things and I don't feel like reimplementing ntpath.normpath in C. If the user does deliberately something stupid he is on his own.

TODO: Backport to 2.6 (maybe 2.5?) and document that users should only do sys.path.append(os.path.normpath(somepath)) if they want to be on the safe side.