Use settings.AUTH_USER_MODEL instead of User directly.

hermes/migrations/0004_auto_20150819_2229.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('hermes', '0003_post_is_published'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='post',
+            name='is_published',
+            field=models.BooleanField(default=False),
+            preserve_default=True,
+        ),
+    ]

hermes/models.py

@@ -6,7 +6,7 @@
 except:
     pass  # Must be python 3
 
-from django.contrib.auth.models import User
+from django.conf import settings as django_settings
 from django.db import models
 from django.utils.text import Truncator, slugify
 from django.utils.translation import ugettext as _
@@ -162,7 +162,7 @@ class Post(TimestampedModel):
     body = models.TextField(_('body'))
 
     category = models.ForeignKey(Category)
-    author = models.ForeignKey(User)
+    author = models.ForeignKey(django_settings.AUTH_USER_MODEL)
 
     objects = PostManager()