recipe-server: Add migration to change username to emails

recipe-server/normandy/base/migrations/0001_copy_email_to_username.py

@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.5 on 2017-03-06 19:25
+from __future__ import unicode_literals
+
+from django.conf import settings
+from django.db import migrations
+
+
+def email_to_username(apps, schema_editor):
+    """
+    Copy emails to usernames for all users.
+    """
+    User = apps.get_model('auth', 'User')
+    for user in User.objects.all():
+        if user.email:
+            user.username = user.email
+            user.save()
+
+
+def remove_email_from_username(apps, schema_editor):
+    """
+    Copy emails to usernames for all users.
+    """
+    User = apps.get_model('auth', 'User')
+    for user in User.objects.all():
+        if '@' in user.username:
+            user.username = user.username.split('@')[0]
+            user.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.RunPython(email_to_username, remove_email_from_username),
+    ]