Refs #16860 -- Fixed password help text when there aren't any validators.

This avoids creating an empty list which is invalid HTML 4.

django/contrib/auth/password_validation.py

@@ -84,7 +84,7 @@ def password_validators_help_text_html(password_validators=None):
     """
     help_texts = password_validators_help_texts(password_validators)
     help_items = [format_html('<li>{}</li>', help_text) for help_text in help_texts]
-    return '<ul>%s</ul>' % ''.join(help_items)
+    return '<ul>%s</ul>' % ''.join(help_items) if help_items else ''
 
 
 class MinimumLengthValidator(object):

tests/auth_tests/test_validators.py

@@ -68,6 +68,10 @@ class PasswordValidationTest(TestCase):
         self.assertEqual(help_text.count('<li>'), 2)
         self.assertIn('12 characters', help_text)
 
+    @override_settings(AUTH_PASSWORD_VALIDATORS=[])
+    def test_empty_password_validator_help_text_html(self):
+        self.assertEqual(password_validators_help_text_html(), '')
+
 
 class MinimumLengthValidatorTest(TestCase):
     def test_validate(self):