[1.6.x] Fixed #21335 -- Use importlib from python3 when using python3

# Taken from Python 2.7 with permission from/by the original author.

import sys

from django.utils import six

def _resolve_name(name, package, level):

    """Return the absolute name of the module to be imported."""

    if not hasattr(package, 'rindex'):

    return "%s.%s" % (package[:dot], name)

if six.PY3:

    from importlib import import_module

else:

    def import_module(name, package=None):

        """Import a module.