Fixed #20761 -- Fixed DatabaseError handling in get_or_create and update_or_create.

from django.conf import settings

from django.core import exceptions

from django.db import connections, router, transaction, DatabaseError

from django.db import connections, router, transaction, DatabaseError, IntegrityError

from django.db.models.constants import LOOKUP_SEP

from django.db.models.fields import AutoField

from django.db.models.query_utils import (Q, select_related_descend,

                return obj, created

        for k, v in six.iteritems(filtered_defaults):

            setattr(obj, k, v)

        try:

        sid = transaction.savepoint(using=self.db)

        try:

            obj.save(update_fields=filtered_defaults.keys(), using=self.db)

            transaction.savepoint_commit(sid, using=self.db)

            return obj, False

        except DatabaseError:

            transaction.savepoint_rollback(sid, using=self.db)

            six.reraise(sys.exc_info())

            six.reraise(*sys.exc_info())

    def _create_object_from_params(self, lookup, params):

        """

        Tries to create an object using passed params.

        Used by get_or_create and update_or_create

        """

        try:

        obj = self.model(**params)

        sid = transaction.savepoint(using=self.db)

        try:

            obj.save(force_insert=True, using=self.db)

            transaction.savepoint_commit(sid, using=self.db)

            return obj, True

        except DatabaseError:

        except DatabaseError as e:

            transaction.savepoint_rollback(sid, using=self.db)

            exc_info = sys.exc_info()

            if isinstance(e, IntegrityError):

                try:

                    return self.get(**lookup), False

                except self.model.DoesNotExist:

                # Re-raise the DatabaseError with its original traceback.

                six.reraise(*exc_info)

                    pass

            six.reraise(*sys.exc_info())

    def _extract_model_params(self, defaults, **kwargs):

        """