django-nose: Fails to see custom user model with --failed

I'm running tests with nose and would like to take advantage of the --failed flag. But as soon as I add it I get errors like these for user related models:

./manage.py test  # works
./manage.py test --failed # fails

CommandError: One or more models did not validate:
vod.video: 'user' has a relation with model accounts.CustomUser, which has either not been installed or is abstract.

Packages:

Django==1.6.7
django-nose==1.3
nose==1.3.4

What am I doing wrong?