Skip the test_built_in_type__integer() test when int.real isn't defined (Python 2.4 and 2.5).

tests/test_context.py

@@ -157,6 +157,17 @@ class GetValueTests(unittest.TestCase, AssertIsMixin):
         item1 = MyInt(10)
         item2 = 10
 
+        try:
+            item2.real
+        except AttributeError:
+            # Then skip this unit test.  The numeric type hierarchy was
+            # added only in Python 2.6, in which case integers inherit
+            # from complex numbers the "real" attribute, etc:
+            #
+            #   http://docs.python.org/library/numbers.html
+            #
+            return
+
         self.assertEquals(item1.real, 10)
         self.assertEquals(item2.real, 10)