match the create api with the update api ... so api is more consistent

app/controllers/posts_controller.rb

@@ -40,11 +40,28 @@ class PostsController < ApplicationController
     post.image_sizes = params[:image_sizes] if params[:image_sizes].present?
     guardian.ensure_can_edit!(post)
 
+    # to stay consistent with the create api, 
+    #  we should allow for title changes and category changes here
+    # we should also move all of this to a post updater.
+    if post.post_number == 1 && (params[:title] || params[:post][:category]) 
+      post.topic.title = params[:title] if params[:title]
+      Topic.transaction do 
+        post.topic.change_category(params[:post][:category])
+        post.topic.save
+      end
+
+      if post.topic.errors.present?
+        render_json_error(post.topic)
+        return
+      end
+    end
+
     revisor = PostRevisor.new(post)
     if revisor.revise!(current_user, params[:post][:raw])
       TopicLink.extract_from(post)
     end
 
+
     if post.errors.present?
       render_json_error(post)
       return