def _virtualenv_sys(venv_path):
    "obtain version and path info from a virtualenv."
    executable = os.path.join(venv_path, env_bin_dir, 'python')
    # Must use "executable" as the first argument rather than as the
    # keyword argument "executable" to get correct value from sys.path
    p = subprocess.Popen([executable,
        '-c', 'import sys;'
              'print (sys.version[:3]);'
              'print ("\\n".join(sys.path));'],
        env={},
        stdout=subprocess.PIPE)
    stdout, err = p.communicate()
    assert not p.returncode and stdout
    lines = stdout.decode('utf-8').splitlines()
    return lines[0], list(filter(bool, lines[1:]))
obtain version and path info from a virtualenv.