Fixed null handling in Value expression

tests/expressions/tests.py

@@ -5,7 +5,7 @@ import datetime
 
 from django.core.exceptions import FieldError
 from django.db import connection, transaction, DatabaseError
-from django.db.models import F
+from django.db.models import F, Value
 from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
 from django.test.utils import Approximate
 from django.utils import six
@@ -174,6 +174,19 @@ class BasicExpressionsTests(TestCase):
             ordered=False
         )
 
+    def test_update_with_none(self):
+        Number.objects.create(integer=1, float=1.0)
+        Number.objects.create(integer=2)
+        Number.objects.filter(float__isnull=False).update(float=Value(None))
+        self.assertQuerysetEqual(
+            Number.objects.all(), [
+                None,
+                None,
+            ],
+            lambda n: n.float,
+            ordered=False
+        )
+
     def test_filter_with_join(self):
         # F Expressions can also span joins
         Company.objects.update(point_of_contact=F('ceo'))