make slug unique (#13053)

passerelle_imio_extra_fees/migrations/0002_auto_20170921_1213.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('passerelle_imio_extra_fees', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='extrafees',
+            name='slug',
+            field=models.SlugField(unique=True),
+        ),
+    ]