bots: Change bot_type to DEFAULT_BOT for bots with None bot_type

Fixes #5440

zerver/migrations/0085_fix_bots_with_none_bot_type.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.2 on 2017-06-20 10:31
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+from django.db.backends.postgresql_psycopg2.schema import DatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+
+def fix_bot_type(apps, schema_editor):
+    # type: (StateApps, DatabaseSchemaEditor) -> None
+    UserProfile = apps.get_model("zerver", "UserProfile")
+    bots = UserProfile.objects.filter(is_bot=True, bot_type=None)
+    for bot in bots:
+        bot.bot_type = 1
+        bot.save()
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('zerver', '0084_realmemoji_deactivated'),
+    ]
+
+    operations = [
+        migrations.RunPython(fix_bot_type),
+    ]