Remove explicit testing of uid and gid in tests of index files.

These tend to be the cause of failures on various systems, they're
not as predictable as we were hoping.

dulwich/tests/test_index.py

@@ -222,9 +222,6 @@ class BuildIndexTests(TestCase):
         self.assertEquals(index_entry[0], index_entry[1])  # ctime and atime
         self.assertTrue(index_entry[0] > time - delta)
         self.assertEquals(index_entry[4], mode)  # mode
-        if sys.platform != 'nt':
-            self.assertEquals(index_entry[5], os.getuid())
-            self.assertEquals(index_entry[6], os.getgid())
         self.assertEquals(index_entry[7], filesize)  # filesize
         self.assertEquals(index_entry[8], sha)  # sha