“Este paquete no debe estar accesible en Python 3” cuando se ejecuta python3

Estaba intentando usar virtualenv para cambiar entre las versiones de python antes de saber que podía usar tanto python como python3 en mi Mac.

Tuve la oportunidad de arreglar mi versión de Python 2.7 para que aún funcione bien, sin embargo, ahora cuando ejecuto Python3, recibo este error:

Failed to import the site module Traceback (most recent call last): File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py", line 544, in  main() File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py", line 530, in main known_paths = addusersitepackages(known_paths) File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py", line 282, in addusersitepackages user_site = getusersitepackages() File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py", line 258, in getusersitepackages user_base = getuserbase() # this will also set USER_BASE File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py", line 248, in getuserbase USER_BASE = get_config_var('userbase') File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/sysconfig.py", line 601, in get_config_var return get_config_vars().get(name) File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/sysconfig.py", line 580, in get_config_vars import _osx_support File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/_osx_support.py", line 4, in  import re File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/re.py", line 125, in  import functools File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/functools.py", line 21, in  from collections import namedtuple File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/collections/__init__.py", line 32, in  from reprlib import recursive_repr as _recursive_repr File "/usr/local/lib/python2.7/site-packages/reprlib/__init__.py", line 7, in  raise ImportError('This package should not be accessible on Python 3. ' ImportError: This package should not be accessible on Python 3. Either you are trying to run from the python-future src folder or your installation of python-future is corrupted. 

Busqué este error en línea, pero la mayor parte de la conversación consistió en arreglar el parche y luego actualizar virtualenv. Sin embargo, esto todavía no soluciona mi problema.

 python3 -V: Python 3.6.0 virtualenv --version: 15.1.0 env | egrep -i 'python|virtualenv': PYTHONPATH=/usr/local/lib/python2.7/site-packages: 

Su entorno contiene PYTHONPATH=/usr/local/lib/python2.7/site-packages

Esto no funciona con Python 3 por razones obvias. Para eliminarlo:

 unset PYTHONPATH 

Resolví mi problema con el siguiente comando

 sudo pip install virtualenv --upgrade virtualenv -p python3 env