[1.9.x] Fixed #26129 -- Made invalid forms display initial values of disabled fields.

Backport of 04564eb74d2d92eaf88b22ab8cec7ef45978111e from master

django/forms/fields.py

@@ -177,6 +177,8 @@ class Field(six.with_metaclass(RenameFieldMethods, object)):
         For most fields, this will simply be data; FileFields need to handle it
         a bit differently.
         """
+        if self.disabled:
+            return initial
         return data
 
     def widget_attrs(self, widget):

docs/releases/1.9.2.txt

@@ -91,3 +91,6 @@ Bugfixes
 
 * Fixed the ``contrib.gis`` map widgets when using
   ``USE_THOUSAND_SEPARATOR=True`` (:ticket:`20415`).
+
+* Made invalid forms display the initial of values of their disabled fields
+  (:ticket:`26129`).

tests/forms_tests/tests/test_forms.py

@@ -718,6 +718,14 @@ class FormsTestCase(SimpleTestCase):
                 {'birthday': datetime.date(1974, 8, 16), 'name': 'John Doe'}
             )
 
+        # Initial data remains present on invalid forms.
+        data = {}
+        f1 = PersonForm(data, initial={'birthday': datetime.date(1974, 8, 16)})
+        f2 = PersonFormFieldInitial(data)
+        for form in (f1, f2):
+            self.assertFalse(form.is_valid())
+            self.assertEqual(form['birthday'].value(), datetime.date(1974, 8, 16))
+
     def test_hidden_data(self):
         class SongForm(Form):
             name = CharField()