[1.1.X] Fixed #12121 -- Modified __reduce__ on a model to avoid an in…

…finite recursion problem that occurs on Python 2.4. Thanks to emulbreh for the report.

Backport of r11691 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@11692 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/base.py

@@ -359,20 +359,25 @@ def __reduce__(self):
         only module-level classes can be pickled by the default path.
         """
         data = self.__dict__
-        if not self._deferred:
-            return super(Model, self).__reduce__()
+        model = self.__class__
+        # The obvious thing to do here is to invoke super().__reduce__()
+        # for the non-deferred case. Don't do that.
+        # On Python 2.4, there is something wierd with __reduce__,
+        # and as a result, the super call will cause an infinite recursion.
+        # See #10547 and #12121.
         defers = []
         pk_val = None
-        for field in self._meta.fields:
-            if isinstance(self.__class__.__dict__.get(field.attname),
-                    DeferredAttribute):
-                defers.append(field.attname)
-                if pk_val is None:
-                    # The pk_val and model values are the same for all
-                    # DeferredAttribute classes, so we only need to do this
-                    # once.
-                    obj = self.__class__.__dict__[field.attname]
-                    model = obj.model_ref()
+        if self._deferred:
+            for field in self._meta.fields:
+                if isinstance(self.__class__.__dict__.get(field.attname),
+                        DeferredAttribute):
+                    defers.append(field.attname)
+                    if pk_val is None:
+                        # The pk_val and model values are the same for all
+                        # DeferredAttribute classes, so we only need to do this
+                        # once.
+                        obj = self.__class__.__dict__[field.attname]
+                        model = obj.model_ref()
 
         return (model_unpickle, (model, defers), data)