Fixed #18719 -- Made force_bytes more consistent with force_text.

django/utils/encoding.py

@@ -122,7 +122,7 @@ def force_bytes(s, encoding='utf-8', strings_only=False, errors='strict'):
             return s
         else:
             return s.decode('utf-8', errors).encode(encoding, errors)
-    if strings_only and (s is None or isinstance(s, int)):
+    if strings_only and is_protected_type(s):
         return s
     if isinstance(s, Promise):
         return six.text_type(s).encode(encoding, errors)

tests/utils_tests/test_encoding.py

@@ -2,11 +2,13 @@
 from __future__ import unicode_literals
 
 import unittest
+import datetime
 
 from django.utils.encoding import force_bytes, filepath_to_uri
 
 
 class TestEncodingUtils(unittest.TestCase):
+
     def test_force_bytes_exception(self):
         """
         Test that force_bytes knows how to convert to bytes an exception
@@ -17,6 +19,10 @@ class TestEncodingUtils(unittest.TestCase):
         result = force_bytes(exc)
         self.assertEqual(result, error_msg.encode('utf-8'))
 
+    def test_force_bytes_strings_only(self):
+        today = datetime.date.today()
+        self.assertEqual(force_bytes(today, strings_only=True), today)
+
     def test_filepath_to_uri(self):
         self.assertEqual(filepath_to_uri('upload\\чубака.mp4'),
             'upload/%D1%87%D1%83%D0%B1%D0%B0%D0%BA%D0%B0.mp4')