Wrong sql query for migration

[mgoldenbe]

I had the model:

class UserInfo(models.Model):
    user = models.ForeignKey(User, related_name='user_info', on_delete=CASCADE)
    picture = models.URLField(null = True, blank = True)
    paying = models.BooleanField(default = False)
    credits = models.DecimalField(max_digits=6, decimal_places=2)
    expiry = models.DateTimeField()
    usd_per_credit = models.FloatField(null = True, blank = True)
    content_count = models.IntegerField(default=0)
    suspended = models.BooleanField(default = False)
    suspended_request = models.TextField(null = True, blank = True)
    suspended_timestamp = models.DateTimeField(null = True, blank = True)

    def __str__(self): return str(self.user)

Then I changed the usd_per_credit field to be

    usd_per_credit = models.FloatField(default = 0.00)

After running makemigrations and migrate, I ran sqlmigrate and got the following:

BEGIN;
--
-- Alter field usd_per_credit on userinfo
--
ALTER TABLE "accounts_userinfo" ALTER COLUMN "usd_per_credit" SET DEFAULT 0.0;
UPDATE "accounts_userinfo" SET "usd_per_credit" = 0.0 WHERE "usd_per_credit" IS NULL;
ALTER TABLE "accounts_userinfo" ALTER COLUMN "usd_per_credit" SET NOT NULL;
ALTER TABLE "accounts_userinfo" ALTER COLUMN "usd_per_credit" DROP DEFAULT;
COMMIT;

The last line before COMMIT is wrong. It drops the default value which was correctly set.