Added field to hold the "main" thread. When connecting reflinks, connect

threads also

boards/migrations/0009_post_thread.py

@@ -0,0 +1,28 b''
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    def first_thread_to_thread(apps, schema_editor):
+        Post = apps.get_model('boards', 'Post')
+        for post in Post.objects.all():
+            post.thread = post.threads.first()
+            post.save(update_fields=['thread'])
+
+
+    dependencies = [
+        ('boards', '0008_auto_20150205_1304'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='post',
+            name='thread',
+            field=models.ForeignKey(related_name='pt+', to='boards.Thread', default=None, null=True),
+            preserve_default=False,
+        ),
+        migrations.RunPython(first_thread_to_thread),
+    ]

boards/models/post.py

@@ -91,6 +91,7 b' class PostManager(models.Manager):'
                            text=pre_text,
                            pub_time=posting_time,
                            poster_ip=ip,
+                           thread=thread,
                            poster_user_agent=UNKNOWN_UA,  # TODO Get UA at
                            # last!
                            last_edit_time=posting_time)
@@ -151,9 +152,12 b' class PostManager(models.Manager):'
                 referenced_post.build_refmap()
                 referenced_post.save(update_fields=['refmap', 'last_edit_time'])
 
-                referenced_thread = referenced_post.get_thread()
-                referenced_thread.last_edit_time = post.pub_time
-                referenced_thread.save(update_fields=['last_edit_time'])
+                referenced_threads = referenced_post.get_threads().all()
+                for thread in referenced_threads:
+                    thread.last_edit_time = post.pub_time
+                    thread.save(update_fields=['last_edit_time'])
+
+                    post.threads.add(thread)
 
     @cached_result
     def get_posts_per_day(self):
@@ -220,6 +224,7 b' class Post(models.Model, Viewable):'
                                               db_index=True)
     refmap = models.TextField(null=True, blank=True)
     threads = models.ManyToManyField('Thread', db_index=True)
+    thread = models.ForeignKey('Thread', db_index=True, related_name='pt+')
 
     def __str__(self):
         return 'P#{}/{}'.format(self.id, self.title)
@@ -299,9 +304,8 b' class Post(models.Model, Viewable):'
 
         return link
 
-    # TODO This must be removed after full transition to multiple threads
     def get_thread(self):
-        return self.get_threads().first()
+        return self.thread
 
     def get_threads(self):
         """