Copied BaseDatabaseCreation._digest() to SchemaEditor to remove dependency.

import hashlib

from django.db.backends.creation import BaseDatabaseCreation

from django.db.backends.utils import truncate_name

from django.db.models.fields.related import ManyToManyField

from django.db.transaction import atomic

    def quote_name(self, name):

        return self.connection.ops.quote_name(name)

    @classmethod

    def _digest(cls, *args):

        """

        Generates a 32-bit digest of a set of arguments that can be used to

        shorten identifying names.

        """

        h = hashlib.md5()

        for arg in args:

            h.update(force_bytes(arg))

        return h.hexdigest()[:8]

    # Field <-> database mapping functions

    def column_sql(self, model, field, include_default=False):

        # If there is just one column in the index, use a default algorithm from Django

        if len(column_names) == 1 and not suffix:

            return truncate_name(

                '%s_%s' % (model._meta.db_table, BaseDatabaseCreation._digest(column_names[0])),

                '%s_%s' % (model._meta.db_table, self._digest(column_names[0])),

                self.connection.ops.max_name_length()

            )

        # Else generate the name for the index using a different algorithm