Why does django 1.7 creates migrations for changes in field choices?

[James Lin]

I have observed this behaviour on version 1.7 but not in previous versions using south migration.

eg.

    class RedemptionCode(models.Model):
        EXPIRE_OPTIONS = (
            ('1 week', '1 Week'),
        )
    
        expire_option = models.CharField(max_length=255, choices=EXPIRE_OPTIONS)

when I added more options:

    EXPIRE_OPTIONS = (
        ('1 week', '1 Week'),
        ('2 weeks', '2 Weeks'),
        ('1 month', '1 Month'),
        ('1 day', '1 Day'),
    )

and run makemigrations, it creates a migration for it, coming from south background I thought it should say no changes detected as it doesn't affects database schema. I don't know what purpose it serves:

    class Migration(migrations.Migration):
    
        dependencies = [
            ('credits', '0001_initial'),
        ]
    
        operations = [
            migrations.AlterField(
                model_name='redemptioncode',
                name='expire_option',
                field=models.CharField(max_length=255, choices=[('1 week', '1 Week'), ('2 weeks', '2 Weeks'), ('1 month', '1 Month'), ('1 day', '1 Day')]),
            ),
        ]

Saw a similar ticket but not sure if it is directly related to this: https://code.djangoproject.com/ticket/23486

[Tim Graham]

See #23581 and #22837.