Make federated server blankable

bookwyrm/migrations/0060_auto_20201030_2010.py

@@ -0,0 +1,19 @@
+# Generated by Django 3.0.7 on 2020-10-30 20:10
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('bookwyrm', '0059_auto_20201030_1755'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='user',
+            name='federated_server',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, to='bookwyrm.FederatedServer'),
+        ),
+    ]

bookwyrm/models/user.py

@@ -24,6 +24,7 @@ class User(OrderedCollectionPageMixin, AbstractUser):
         'FederatedServer',
         on_delete=models.PROTECT,
         null=True,
+        blank=True,
     )
     outbox = models.CharField(max_length=255, unique=True)
     summary = models.TextField(blank=True, null=True)