Fixed #19942 -- Decoded errors coming from Popen commands

import os

from subprocess import PIPE, Popen

from django.utils.encoding import force_text, DEFAULT_LOCALE_ENCODING

def popen_wrapper(args):

    """

    p = Popen(args, shell=False, stdout=PIPE, stderr=PIPE,

              close_fds=os.name != 'nt', universal_newlines=True)

    output, errors = p.communicate()

    return output, errors, p.returncode

    return (

        output,

        force_text(errors, DEFAULT_LOCALE_ENCODING, strings_only=True),

        p.returncode

    )

def handle_extensions(extensions=('html',), ignored=('py',)):

    """