Fixed a couple of test failures on Windows.

import os

from django.utils import unittest

from django.utils._os import safe_join

class SafeJoinTests(unittest.TestCase):

    def test_base_path_ends_with_sep(self):

        drive, path = os.path.splitdrive(safe_join("/abc/", "abc"))

        self.assertEqual(

            safe_join("/abc/", "abc"),

            "/abc/abc",

            path,

            "{0}abc{0}abc".format(os.path.sep)

        )

    def test_root_path(self):

        drive, path = os.path.splitdrive(safe_join("/", "path"))

        self.assertEqual(

            safe_join("/", "path"),

            "/path",

            path,

            "{0}path".format(os.path.sep),

        )

        drive, path = os.path.splitdrive(safe_join("/", ""))

        self.assertEqual(

            safe_join("/", ""),

            "/",

            path,

            os.path.sep,

        )