[1.11.x] Fixed #28387 -- Fixed has_changed() for disabled form fields that subclass it.

Backport of 5debbdfcc8 from master

tests/forms_tests/field_tests/test_booleanfield.py

@@ -59,3 +59,7 @@ class BooleanFieldTest(SimpleTestCase):
         self.assertFalse(f.has_changed(True, 'True'))
         self.assertTrue(f.has_changed(False, 'True'))
         self.assertTrue(f.has_changed(True, 'False'))
+
+    def test_disabled_has_changed(self):
+        f = BooleanField(disabled=True)
+        self.assertIs(f.has_changed('True', 'False'), False)

tests/forms_tests/field_tests/test_filefield.py

@@ -77,5 +77,9 @@ class FileFieldTest(SimpleTestCase):
         # with here)
         self.assertTrue(f.has_changed('resume.txt', {'filename': 'resume.txt', 'content': 'My resume'}))
 
+    def test_disabled_has_changed(self):
+        f = FileField(disabled=True)
+        self.assertIs(f.has_changed('x', 'y'), False)
+
     def test_file_picklable(self):
         self.assertIsInstance(pickle.loads(pickle.dumps(FileField())), FileField)

tests/forms_tests/field_tests/test_multiplechoicefield.py

@@ -70,3 +70,7 @@ class MultipleChoiceFieldTest(SimpleTestCase):
         self.assertFalse(f.has_changed([2, 1], ['1', '2']))
         self.assertTrue(f.has_changed([1, 2], ['1']))
         self.assertTrue(f.has_changed([1, 2], ['1', '3']))
+
+    def test_disabled_has_changed(self):
+        f = MultipleChoiceField(choices=[('1', 'One'), ('2', 'Two')], disabled=True)
+        self.assertIs(f.has_changed('x', 'y'), False)

tests/forms_tests/field_tests/test_multivaluefield.py

@@ -103,6 +103,10 @@ class MultiValueFieldTest(SimpleTestCase):
             ['some text', ['J', 'P'], ['2009-04-25', '11:44:00']],
         ))
 
+    def test_disabled_has_changed(self):
+        f = MultiValueField(fields=(CharField(), CharField()), disabled=True)
+        self.assertIs(f.has_changed(['x', 'x'], ['y', 'y']), False)
+
     def test_form_as_table(self):
         form = ComplexFieldForm()
         self.assertHTMLEqual(