Use get_user_model

gestioncof/forms.py

@@ -1,6 +1,6 @@
 from django import forms
+from django.contrib.auth import get_user_model
 from django.contrib.auth.forms import AuthenticationForm
-from django.contrib.auth.models import User
 from django.forms.formsets import BaseFormSet, formset_factory
 from django.forms.widgets import CheckboxSelectMultiple, RadioSelect
 from django.utils.translation import ugettext_lazy as _
@@ -10,6 +10,8 @@ from bda.models import Spectacle
 from gestioncof.models import CalendarSubscription, Club, CofProfile, EventCommentValue
 from gestioncof.widgets import TriStateCheckbox
 
+User = get_user_model()
+
 
 class ExteAuthenticationForm(AuthenticationForm):
     """