fall back when an old test_support doesn't have various data and functions (closes #17533)

Lib/test/pickletester.py

@@ -6,8 +6,14 @@ import cStringIO
 import pickletools
 import copy_reg
 
-from test.test_support import (TestFailed, have_unicode, TESTFN, _2G, _1M,
-                               precisionbigmemtest)
+from test.test_support import TestFailed, verbose, have_unicode, TESTFN
+try:
+    from test.test_support import _2G, _1M, precisionbigmemtest
+except ImportError:
+    # this import might fail when run on older Python versions by test_xpickle
+    _2G = _1G = 0
+    def precisionbigmemtest(*args, **kwargs):
+        return lambda self: None
 
 # Tests that try a number of pickle protocols should have a
 #     for proto in protocols:

Misc/NEWS

@@ -24,6 +24,8 @@ Library
 - Issue #17531: Fix tests that thought group and user ids were always the int
   type. Also, always allow -1 as a valid group and user id.
 
+- Issue #17533: Fix test_xpickle with older versions of Python 2.5.
+
 Documentation
 -------------