avec les migrations c'est mieux

equipment/migrations/0014_auto_20180827_0005.py

@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.11 on 2018-08-26 22:05
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('equipment', '0013_auto_20180826_1949'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='equipment',
+            name='owner',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, to='auth.Group', verbose_name='propriétaire'),
+        ),
+        migrations.AlterField(
+            model_name='equipmentcategory',
+            name='parent',
+            field=models.ForeignKey(blank=True, default=None, help_text='merci de ne pas faire de référence cyclique', null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='children', to='equipment.EquipmentCategory', verbose_name='parent'),
+        ),
+    ]