Ticket #17254: backends.diff

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< from django.contrib.auth.models import User, Permission
---
> from django.contrib.auth.models import User, Permission, AnonymousUser
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>     
>     user_model = User
>     permission_model = Permission
>     anonymous_user_model = AnonymousUser
>     
>     def get_anonymous_user(self):
>         return AnonymousUser()
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<             user = User.objects.get(username=username)
---
>             user = self.user_model.objects.get(username=username)
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<         except User.DoesNotExist:
---
>         except self.user_model.DoesNotExist:
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<                 perms = Permission.objects.all()
---
>                 perms = self.permission_model.objects.all()
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<                 perms = Permission.objects.filter(group__user=user_obj)
---
>                 perms = self.permission_model.objects.filter(group__user=user_obj)
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<             return User.objects.get(pk=user_id)
<         except User.DoesNotExist:
---
>             return self.user_model.objects.get(pk=user_id)
>         except self.user_model.DoesNotExist:
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<             user, created = User.objects.get_or_create(username=username)
---
>             user, created = self.user_model.objects.get_or_create(username=username)
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<                 user = User.objects.get(username=username)
<             except User.DoesNotExist:
---
>                 user = self.user_model.objects.get(username=username)
>             except self.user_model.DoesNotExist: