ERROR: virtualenv is not compatible with this system or executable

I got the following errors:

$ virtualenv .env
Using base prefix '/Users/izeye/anaconda'
New python executable in /Users/izeye/.env/bin/python
ERROR: The executable /Users/izeye/.env/bin/python is not functioning
ERROR: It thinks sys.prefix is '/Users/izeye' (should be '/Users/izeye/.env')
ERROR: virtualenv is not compatible with this system or executable
$

I just gave up to use Python 3 and worked around with Python 2 as follows:

$ virtualenv .env -p python2
Running virtualenv with interpreter /Library/Frameworks/Python.framework/Versions/2.7/bin/python2
New python executable in /Users/izeye/.env/bin/python
Installing setuptools, pip, wheel...done.
$