Fix tests on python3.

dulwich/objects.py

@@ -1015,7 +1015,9 @@ class Tree(ShaFile):
                                           True):
             check_hexsha(sha, 'invalid sha %s' % sha)
             if b'/' in name or name in (b'', b'.', b'..', b'.git'):
-                raise ObjectFormatException('invalid name %s' % name)
+                raise ObjectFormatException(
+                        'invalid name %s' %
+                        name.decode('utf-8', 'replace'))
 
             if mode not in allowed_modes:
                 raise ObjectFormatException('invalid mode %06o' % mode)

dulwich/tests/test_porcelain.py

@@ -1304,7 +1304,7 @@ class FsckTests(PorcelainTestCase):
     def test_git_dir(self):
         obj = Tree()
         a = Blob()
-        a.data = "foo"
+        a.data = b"foo"
         obj.add(b".git", 0o100644, a.id)
         self.repo.object_store.add_objects(
             [(a, None), (obj, None)])