old_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals
  
  from django.db import models, migrations
  import django.utils.timezone
  import guardian.mixins
  import django.core.validators
  
  
  class Migration(migrations.Migration):
  
      dependencies = [
          ('testapp', '0005_auto_20151217_2344'),
      ]
  
      operations = [
          migrations.CreateModel(
              name='CustomUsernameUser',
              fields=[
                  ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
                  ('password', models.CharField(max_length=128, verbose_name='password')),
                  ('last_login', models.DateTimeField(default=django.utils.timezone.now, verbose_name='last login')),
                  ('email', models.EmailField(unique=True, max_length=100)),
              ],
              options={
                  'abstract': False,
              },
              bases=(models.Model, guardian.mixins.GuardianUserMixin),
          ),
          migrations.AlterField(
              model_name='customuser',
              name='email',
              field=models.EmailField(max_length=75, verbose_name='email address', blank=True),
              preserve_default=True,
          ),
          migrations.AlterField(
              model_name='customuser',
              name='groups',
              field=models.ManyToManyField(related_query_name='user', related_name='user_set', to='auth.Group', blank=True, help_text='The groups this user belongs to. A user will get all permissions granted to each of his/her group.', verbose_name='groups'),
              preserve_default=True,
          ),
          migrations.AlterField(
              model_name='customuser',
              name='last_login',
              field=models.DateTimeField(default=django.utils.timezone.now, verbose_name='last login'),
              preserve_default=True,
          ),
          migrations.AlterField(
              model_name='customuser',
              name='username',
              field=models.CharField(help_text='Required. 30 characters or fewer. Letters, digits and @/./+/-/_ only.', unique=True, max_length=30, verbose_name='username', validators=[django.core.validators.RegexValidator('^[\\w.@+-]+$', 'Enter a valid username.', 'invalid')]),
              preserve_default=True,
          ),
      ]
  
new_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals
  
  from django.db import models, migrations
  import django.utils.timezone
  import guardian.mixins
  import django.core.validators
  
  
  class Migration(migrations.Migration):
  
      dependencies = [
          ('testapp', '0005_auto_20151217_2344'),
      ]
  
      operations = [
          migrations.CreateModel(
              name='CustomUsernameUser',
              fields=[
                  ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
                  ('password', models.CharField(max_length=128, verbose_name='password')),
                  ('last_login', models.DateTimeField(default=django.utils.timezone.now, verbose_name='last login')),
                  ('email', models.EmailField(unique=True, max_length=100)),
              ],
              options={
                  'abstract': False,
              },
              bases=(models.Model, guardian.mixins.GuardianUserMixin),
          )
      ]
  
subject: Remove everything from migrations that has nothing to do with `CustomUsernameUser`