Fixed #18839 - Field.__init__() now calls super().

django/forms/fields.py

@@ -120,6 +120,7 @@ class Field(object):
         self.error_messages = messages
 
         self.validators = self.default_validators + validators
+        super(Field, self).__init__()
 
     def prepare_value(self, value):
         return value

docs/releases/1.6.txt

@@ -163,6 +163,10 @@ Minor features
 
 * The :djadmin:`diffsettings` comand gained a ``--all`` option.
 
+* :func:`django.forms.fields.Field.__init__` now calls ``super()``, allowing
+  field mixins to implement ``__init__()`` methods that will reliably be
+  called.
+
 Backwards incompatible changes in 1.6
 =====================================
 

tests/forms_tests/tests/fields.py

@@ -63,6 +63,20 @@ class FieldsTests(SimpleTestCase):
         self.assertTrue(Field(required=True).widget.is_required)
         self.assertFalse(Field(required=False).widget.is_required)
 
+    def test_cooperative_multiple_inheritance(self):
+        class A(object):
+            def __init__(self):
+                self.class_a_var = True
+                super(A, self).__init__()
+
+
+        class ComplexField(Field, A):
+            def __init__(self):
+                super(ComplexField, self).__init__()
+
+        f = ComplexField()
+        self.assertTrue(f.class_a_var)
+
     # CharField ###################################################################
 
     def test_charfield_1(self):