Migrations depending on django.contrib.auth with custom User model fail

[Ilya Semenov]

Steps to reproduce:

1. Create a new project and the new app accounts
2. Create the model accounts.User:

   from django.contrib.auth import models as auth_models
   from django.db import models
   
   class User(auth_models.AbstractBaseUser, auth_models.PermissionsMixin):
           name = models.CharField(max_length=255, unique=True)
           USERNAME_FIELD = 'name'
   

3. Edit settings.py and set AUTH_USER_MODEL = 'accounts.User'
4. Run manage.py makemigrations accounts. It will crash:

   ...
     File "/Users/semenov/work/migrtest/venv/src/django/django/db/migrations/graph.py", line 42, in add_dependency
       raise KeyError("Dependency references nonexistent parent node %r" % (parent,))
   KeyError: u"Dependency references nonexistent parent node (u'auth', u'__last__')"
   

This started to happen 2 days ago, I bisected the cause to aba75e73db6a0baca1b721698ca24f026bb4a745 (the fix for #22970). Previously, the migration dependencies were set to [('auth', '__first__')] which worked fine. (I realize that __last__ makes more sense, so this is not about reverting the fix but rather making __last__ to work on django.contrib.auth.migrations.)

[Tim Graham]

makemigrations works fine for me, it's not until migrate that I get the error.

[Ilya Semenov]

My bad, that's right, it's migrate that fails.

[Tim Graham]

#23021 reported this for contenttypes.

[Florian Apolloner]

This seems to be caused by the fact that we have '__last__' and '__latest__'. (Changing the file to '__latest__' makes migrate work fine). @andrew: Which of the two did you intend in the beginning?

[Andrew Godwin]

Yeah, it's meant to be __latest__, error on my part in the fix for the previous bug. Will fix it tonight if nobody gets there first.

[Tim Graham <timograham@…>]

In 9a2ab629776735fae2c9184dc4b9d9029bad15b2:

Fixed #23008 -- Fixed typo causing bad migration dependencies.

Thanks semenov for the report and Florian for investigation.

[Tim Graham <timograham@…>]

In fe5f29eb1db795257d4095df0e1547c17daadade:

[1.7.x] Fixed #23008 -- Fixed typo causing bad migration dependencies.

Thanks semenov for the report and Florian for investigation.

Backport of 9a2ab62977 from master