new_contents: # -*- coding: utf-8 -*-
  # Generated by Django 1.11.13 on 2018-06-28 19:59
  from __future__ import unicode_literals
  
  from django.db import migrations, models
  import django.db.models.deletion
  
  
  class Migration(migrations.Migration):
  
      dependencies = [
          ('devices', '0006_device_used_in'),
      ]
  
      operations = [
          migrations.AlterField(
              model_name='device',
              name='used_in',
              field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, to='devices.Device'),
          ),
      ]
  
subject: add missing Devince migration