Fix tests on Python3.

dulwich/tests/test_index.py

@@ -484,7 +484,7 @@ class TestTreeFSPathConversion(TestCase):
 
     def test_tree_to_fs_path(self):
         tree_path = u'délwíçh/foo'.encode('utf8')
-        fs_path = _tree_to_fs_path('/prefix/path', tree_path)
+        fs_path = _tree_to_fs_path(b'/prefix/path', tree_path)
         self.assertEqual(
             fs_path,
             os.path.join(u'/prefix/path', u'délwíçh', u'foo').encode('utf8'))