[py3] Fix encoding issues in contrib.sessions

from __future__ import unicode_literals

import base64

import time

from datetime import datetime, timedelta

from django.utils.crypto import get_random_string

from django.utils.crypto import salted_hmac

from django.utils import timezone

from django.utils.encoding import smart_bytes

class CreateError(Exception):

    """

        "Returns the given session dictionary pickled and encoded as a string."

        pickled = pickle.dumps(session_dict, pickle.HIGHEST_PROTOCOL)

        hash = self._hash(pickled)

        return base64.encodestring(hash + ":" + pickled)

        return base64.encodestring(hash.encode() + b":" + pickled)

    def decode(self, session_data):

        encoded_data = base64.decodestring(session_data)

        encoded_data = base64.decodestring(smart_bytes(session_data))

        try:

            # could produce ValueError if there is no ':'

            hash, pickled = encoded_data.split(':', 1)

            hash, pickled = encoded_data.split(b':', 1)

            expected_hash = self._hash(pickled)

            if not constant_time_compare(hash, expected_hash):

            if not constant_time_compare(hash.decode(), expected_hash):

                raise SuspiciousOperation("Session data corrupted")

            else:

                return pickle.loads(pickled)

from django.contrib.sessions.backends.base import SessionBase, CreateError

from django.core.exceptions import SuspiciousOperation

from django.db import IntegrityError, transaction, router

from django.utils.encoding import force_text

from django.utils import timezone

                session_key = self.session_key,

                expire_date__gt=timezone.now()

            )

            return self.decode(force_text(s.session_data))

            return self.decode(s.session_data)

        except (Session.DoesNotExist, SuspiciousOperation):

            self.create()

            return {}