fix bin-file test in ipython3

IPython/html/tests/test_files.py

@@ -92,8 +92,7 @@ class FilesTest(NotebookTestBase):
         r = requests.get(url_path_join(base, 'files', 'test.bin'))
         self.assertEqual(r.status_code, 200)
         self.assertEqual(r.headers['content-type'], 'application/octet-stream')
-
-        self.assertEqual(binascii.hexlify(r.content[0]), 'ff')
+        self.assertEqual(r.content[0], 255)
         self.assertEqual(len(r.content), 6)
 
         r = requests.get(url_path_join(base, 'files', 'test.txt'))