Don't run tutorial doc tests on windows.

dulwich/tests/__init__.py

@@ -186,7 +186,7 @@ def compat_test_suite():
 def test_suite():
     result = unittest.TestSuite()
     result.addTests(self_test_suite())
-    if sys.version_info[0] == 2:
+    if sys.version_info[0] == 2 and sys.platform != 'win32':
         result.addTests(tutorial_test_suite())
     from dulwich.tests.compat import test_suite as compat_test_suite
     result.addTests(compat_test_suite())