Sorry, I haven't installed python 3.*, I just have default Mac OS python 2.7.

Here's a minimal test case. Tar expands to
 file structure:                                                                                                 
  ./test.py                                                                                                      
  ./en/LC_MESSAGES/messages.po   

$ ./test.py 

Traceback (most recent call last):
  File "./test.py", line 28, in <module>
    test()
  File "./test.py", line 23, in test
    gettext.install('messages', localedir=LOCALEDIR)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/gettext.py", line 494, in install
    t = translation(domain, localedir, fallback=True, codeset=codeset)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/gettext.py", line 479, in translat\
ion
    t = _translations.setdefault(key, class_(fp))
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/gettext.py", line 180, in __init__
    self._parse(fp)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/gettext.py", line 314, in _parse
    v = v.split(';')
AttributeError: 'list' object has no attribute 'split'