When running the OS X 32-bit-only installer 2.7.4rc1 on OS X 10.5, test_xpickle has many test failures all in CPicklePython25Compat.  Note, there is an Apple-supplied system Python 2.5 shipped on OS X 10.5. (There is also an Apple-supplied system Python 2.5 shipped on OS X 10.8, too, but for some reason, the test doesn't report a failure there.)  The use of precisionbigmemtest appears to have been added by 680959a3ae2e for Issue13555.

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ERROR: test_attribute_name_interning (test.test_xpickle.CPicklePython25Compat)
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Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/pickletester.py", line 983, in test_attribute_name_interning
    s = self.dumps(x, proto)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/test_xpickle.py", line 115, in dumps
    return self.send_to_worker(self.python, arg, proto)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/test_xpickle.py", line 111, in send_to_worker
    raise RuntimeError(stderr)
RuntimeError: Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/test_xpickle.py", line 28, in <module>
    exec compile(open(mod_path).read(), mod_path, 'exec') in pickletester.__dict__
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/pickletester.py", line 9, in <module>
    from test.test_support import (TestFailed, have_unicode, TESTFN, _2G, _1M,
ImportError: cannot import name precisionbigmemtest

[...]
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Ran 180 tests in 5.033s

FAILED (errors=67)

"precisionbigmemtest" was added in a 2.5 bug fix release. I suppose Tiger has an older version.

Right. precisionbigmemtest was added by 0aafd1ae5120 ("security patches from Apple") and released in 2.5.3. OS X 10.5 ("Leopard") has 2.5.1. On a hunch, I installed a python2.4 (2.4.4) and the tests are broken using that as well: multiple failures attempting to import _2G


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ERROR: test_simple_newobj (test.test_xpickle.CPicklePython24Compat)
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Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/pickletester.py", line 877, in test_simple_newobj
    s = self.dumps(x, proto)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/test_xpickle.py", line 115, in dumps
    return self.send_to_worker(self.python, arg, proto)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/test_xpickle.py", line 111, in send_to_worker
    raise RuntimeError(stderr)
RuntimeError: Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/test_xpickle.py", line 28, in ?
    exec compile(open(mod_path).read(), mod_path, 'exec') in pickletester.__dict__
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/test/pickletester.py", line 9, in ?
    from test.test_support import (TestFailed, have_unicode, TESTFN, _2G, _1M,
ImportError: cannot import name _2G

Can you try the attached patch?

There's a typo in the patch and None won't work. With the following change to the patch:

-    _2G = _1G = None
+    _2G = _1M = 0

the test passes on OS X 10.5 against the system 2.5.1 and an installed 2.4.4.  Thanks!

New changeset de48977f9289 by Benjamin Peterson in branch '2.7':
fall back when an old test_support doesn't have various data and functions (closes #17533)
http://hg.python.org/cpython/rev/de48977f9289

Benjamin, the fix you committed still has the _1G vs. _1M typo.

New changeset be0586ebb842 by Benjamin Peterson in branch '2.7':
G -> M (closes #17533)
http://hg.python.org/cpython/rev/be0586ebb842