Add migration to populate Page.last_published_at from latest_revision_created_at

wagtail/wagtailcore/migrations/0036_populate_page_last_published_at.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.1 on 2017-06-01 11:03
+from __future__ import unicode_literals
+
+from django.db import migrations
+from django.db.models import F
+
+
+def forwards_func(apps, schema_editor):
+    Page = apps.get_model("wagtailcore", "Page")
+    Page.objects.filter(has_unpublished_changes=False).update(last_published_at=F('latest_revision_created_at'))
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('wagtailcore', '0035_page_last_published_at'),
+    ]
+
+    operations = [
+        migrations.RunPython(forwards_func, migrations.RunPython.noop),
+    ]