Patch fixing the issues raised in r.david.murray's review:

* Merged _find_linux_release_file() back into linux_distribution() and broke out _UNIXCONFDIR module level variable to enable mocking of the unittest data
* Fix already present style issue in linux_distribution() code
* Separate test_dist_with_unicode() into test_dist_with_utf8 and test_dist_with_latin1
* Moved test data into the setUp() method and broke long lines to under 79 chars
* Switched from NamedTempfile() to TemporaryDirectory() => I think this fixes the Windows incompatibility but I can mark the tests as Skip on Windows if that isn't true (I don't have a Windows box to test on).
* Removed Misc/NEWS portion of patch

* I've switched from os.environ['LC_ALL'] = temp_locale to  setlocale(locale.LC_ALL, temp_locale).  Testing showed that the former did not provoke the bug while the latter does.  Could someone point me at documentation on the difference between these two?  I'd like to understand what the two different calls do differently so that I use them correctly in other unittests.