Initial look at the failures on the stable buildbots:

FreeBSD 10.x: if locale coercion succeeds, we then fail on get_codeset() (perhaps because that doesn't recognise LC_CTYPE=UTF-8?)
FreeBSD CURRENT: if locale coercion fails (due to no suitable locale), lots of error handling tests fail due to the unexpected warning message on stderr

Mac OS X Tiger: looks like the test expectations aren't right on Mac OS X (at least for Tiger). I've added the Mac OS X folks to the nosy list.

Ubuntu shared library build: loading the shared library fails in _testembed for the `test_forced_io_encoding` test case, which suggest a problem with the way that particular test is running the binary

Windows 8.1 refleak hunting: failure doesn't appear to be due to this change (multiprocessing test failures)
s390x RHEL 7: failure doesn't appear to be due to this change (multiprocessing test failures)