Migrate Fails When Column is Deleted and Unique Together is modified in the same migration

[Chris Reedy]

I discovered a bug that causes a migration to fail when a column is deleted in a migration and unique together is modified in the same migration. The following are the steps to reproduce the bug:

   # Consider this your model:
   class Fruit (models.Model):
     taste = models.CharField(max_length=40)
     color = models.CharField(max_length=40)
     shape = models.CharField(max_length=40)

        class Meta:
          unique_together = ('taste', 'color', 'shape')

Now, if you delete the field 'shape' and remove it from the unique together in the same migration so the model looks as follows:

   # Updated model:
   class Fruit (models.Model):
        taste = models.CharField(max_length=40)
        color = models.CharField(max_length=40)

        class Meta:
          unique_together = ('taste', 'color')
}}
Migration will fail in modifying the unique_together and throw an error that the Fruit has no field named 'shape'  I think that this is because the delete of the column is processed before the unique index is updated.

[Tim Graham]

Duplicate of #26180