FIX: Moving a post should also update its TopicLink records

app/models/post_mover.rb

@@ -79,6 +79,9 @@ class PostMover
       id: post.id,
       topic_id: original_topic.id
     )
+
+    # Move any links from the post to the new topic
+    post.topic_links.update_all(topic_id: destination_topic.id)
   end
 
   def update_statistics

spec/models/topic_spec.rb

@@ -234,7 +234,7 @@ describe Topic do
     let(:category) { Fabricate(:category, user: user) }
     let!(:topic) { Fabricate(:topic, user: user, category: category) }
     let!(:p1) { Fabricate(:post, topic: topic, user: user) }
-    let!(:p2) { Fabricate(:post, topic: topic, user: another_user)}
+    let!(:p2) { Fabricate(:post, topic: topic, user: another_user, raw: "Has a link to [evil trout](http://eviltrout.com) which is a cool site.")}
     let!(:p3) { Fabricate(:post, topic: topic, user: user)}
     let!(:p4) { Fabricate(:post, topic: topic, user: user)}
 
@@ -279,6 +279,7 @@ describe Topic do
       before do
         topic.expects(:add_moderator_post)
         TopicUser.update_last_read(user, topic.id, p4.post_number, 0)
+        TopicLink.extract_from(p2)
       end
 
       context "to a new topic" do
@@ -303,6 +304,7 @@ describe Topic do
           p2.reload
           p2.sort_order.should == 1
           p2.post_number.should == 1
+          p2.topic_links.first.topic_id.should == new_topic.id
 
           p4.reload
           p4.post_number.should == 2