It doesn't work when Python2 is the only installed python either:  

    (bitmask)jeremy@ubuntu:~/Code/bitmask$ python2 setup.py develop
    running develop
    Checking .pth file support in /usr/local/lib/python2.7/dist-packages/
    error: can't create or remove files in install directory
    
    The following error occurred while trying to add or remove files in the
    installation directory:
    
    [Errno 13] Permission denied: '/usr/local/lib/python2.7/dist-packages/test-easy-install-4094.pth'

    The installation directory you specified (via --install-dir, --prefix, or
    the distutils default setting) was:

    /usr/local/lib/python2.7/dist-packages/

    Perhaps your account does not have write access to this directory?  If the
    installation directory is a system-owned directory, you may need to sign in
    as the administrator or "root" account.  If you do not have administrative
    access to this machine, you may wish to choose a different installation
    directory, preferably one that is listed in your PYTHONPATH environment
    variable.

    For information on other options, you may wish to consult the
    documentation at:

      http://packages.python.org/distribute/easy_install.html

    Please make the appropriate changes for your system and try again.
    
    (bitmask)jeremy@ubuntu:~/Code/bitmask$