X> python2.7
Python 2.7.15 (default, Jun 27 2018, 13:05:28) 
[GCC 8.1.1 20180531] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pex
>>> from pex.platforms import Platform
>>> Platform.current()
Platform(platform='linux_x86_64', impl='cp', version='27', abi='cp27mu')
>>> dir(pex)
['__builtins__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', 'glibc', 'pep425tags', 'platforms']
>>> pex.platforms
<module 'pex.platforms' from '/usr/lib/python2.7/site-packages/pex-1.4.3_test-py2.7.egg/pex/platforms.pyc'>
>>> Platform.current().platform
'linux_x86_64'
>>> '-'.join(Platform.current())
'linux_x86_64-cp-27-cp27mu'

on this linux laptop -- will do a pants repl to see if that's different (using the pants version of pex)