Registering custom Admin class for User model breaks changing passwords

[django.bigfudge@…]

I am doing this:

class UserProfileInline(admin.StackedInline):

model = UserProfile

class UserAdmin(admin.ModelAdmin):

save_on_top = True
inlines = [UserProfileInline]

admin.site.unregister(User)
admin.site.register(User, UserAdmin)

To allow me to edit UserProfiles inline with Users. However, doing this seems to break the password reset feature within django admin (not the user-facing password reset – the one on the User model itself which allows and administrator to set a user's password manually. The error is:

user object with primary key u'3/password' does not exist.