Fixed #12455 -- corrected an oversight in result_headers not honoring admin_order_field

This finishes some slightly refactoring that went into the admin_list
template tags.

Thanks to kegan for discovering the oversight.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12157 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/admin_util/models.py

@@ -1 +1,18 @@
-# needed for tests
+from django.db import models
+
+
+
+class Article(models.Model):
+    """
+    A simple Article model for testing
+    """
+    title = models.CharField(max_length=100)
+    title2 = models.CharField(max_length=100, verbose_name="another name")
+    created = models.DateTimeField()
+
+    def test_from_model(self):
+        return "nothing"
+
+    def test_from_model_with_override(self):
+        return "nothing"
+    test_from_model_with_override.short_description = "not what you expect"