m2ms with intermediaries break manage.py reset

[Dougal Sutherland]

Using the new intermediaries on many-to-many models breaks the functionality of manage.py reset for me.

More specifically, if I create a project "testing" and an application "tests", and put the following models in:

class Band(models.Model):
    name = models.CharField(max_length=100)

class Musician(models.Model):
    name = models.CharField(max_length=100)
    bands = models.ManyToManyField(Band, through='Membership')

class Membership(models.Model):
    band = models.ForeignKey(Band)
    musician = models.ForeignKey(Musician)
    join_date = models.DateField()

after syncdb'ing, if I then try "manage.py reset tests", I get an error message. Looking at "manage.py sqlclear tests", I get the following output:

BEGIN;
DROP TABLE "tests_membership";
DROP TABLE "tests_membership";
DROP TABLE "tests_musician";
DROP TABLE "tests_band";
COMMIT;

This duplication comes from django.core.management.sql.sql_delete, because said function outputs the drop statement for all app models and then for all many-to-many tables. The fix is simple: switch the skip-this-relation condition from checking if the relation is a generic relation to checking the new .creates_table attribute. A patch which does this is attached.

[Russell Keith-Magee]

(In [8157]) Fixed #8053 -- Corrected a bug with reset and m2m intermediate tables. Thanks to d00gs for the report and fix.