Fixed #35139 -- Prevented file read after ImageField is saved to storage.

tests/model_fields/test_imagefield.py

@@ -18,6 +18,7 @@ if Image:
     from .models import (
         Person,
         PersonDimensionsFirst,
+        PersonNoReadImage,
         PersonTwoImages,
         PersonWithHeight,
         PersonWithHeightAndWidth,
@@ -30,7 +31,7 @@ else:
         pass
 
     PersonWithHeight = PersonWithHeightAndWidth = PersonDimensionsFirst = Person
-    PersonTwoImages = Person
+    PersonTwoImages = PersonNoReadImage = Person
 
 
 class ImageFieldTestMixin(SerializeMixin):
@@ -469,3 +470,28 @@ class TwoImageFieldTests(ImageFieldTestMixin, TestCase):
         # Dimensions were recalculated, and hence file should have opened.
         self.assertIs(p.mugshot.was_opened, True)
         self.assertIs(p.headshot.was_opened, True)
+
+
+@skipIf(Image is None, "Pillow is required to test ImageField")
+class NoReadTests(ImageFieldTestMixin, TestCase):
+    def test_width_height_correct_name_mangling_correct(self):
+        instance1 = PersonNoReadImage()
+
+        instance1.mugshot.save("mug", self.file1)
+
+        self.assertEqual(instance1.mugshot_width, 4)
+        self.assertEqual(instance1.mugshot_height, 8)
+
+        instance1.save()
+
+        self.assertEqual(instance1.mugshot_width, 4)
+        self.assertEqual(instance1.mugshot_height, 8)
+
+        instance2 = PersonNoReadImage()
+        instance2.mugshot.save("mug", self.file1)
+        instance2.save()
+
+        self.assertNotEqual(instance1.mugshot.name, instance2.mugshot.name)
+
+        self.assertEqual(instance1.mugshot_width, instance2.mugshot_width)
+        self.assertEqual(instance1.mugshot_height, instance2.mugshot_height)