The patch LGTM. And I agree that the fix is not needed for 3.4.  Thanks, Serhiy.

I verified that it does solve the "embedded" problem (case 1 above) when using embedded versions of all previous releases of 2.7.x (except 2.7.0) and 3.3.x.

For the record, it appears 2.7.1 introduced a separate incompatibility issue that causes a similar initialization crash with an embedded version of 2.7.0:

Traceback (most recent call last):
  File "/py/test_issue18050/root/lib/python2.7/site.py", line 62, in <module>
    import os
  File "/py/test_issue18050/root/lib/python2.7/os.py", line 398, in <module>
    import UserDict
  File "/py/test_issue18050/root/lib/python2.7/UserDict.py", line 83, in <module>
    import _abcoll
  File "/py/test_issue18050/root/lib/python2.7/_abcoll.py", line 11, in <module>
    from abc import ABCMeta, abstractmethod
  File "/py/test_issue18050/root/lib/python2.7/abc.py", line 8, in <module>
    from _weakrefset import WeakSet
  File "/py/test_issue18050/root/lib/python2.7/_weakrefset.py", line 5, in <module>
    from _weakref import ref
ImportError: No module named _weakref

Googling shows a number of reports of users who have run into that one, too, though no one seems to have opened an issue here about it.  I don't think it's worth trying to fix that one at this point as there probably aren't that many instances of system executables that still have embedded static 2.7.0 interpreters anymore (I hope).  Unfortunately, that's not the case for embedded static 2.7.2, e.g. vim on OS X 10.8.x.