Fix post_update_count increment test.

7) Failure:
PostTest#test_: Tagging: A post that has been updated should increment the updater's post_update_count. [/home/danbooru/src/danbooru/test/unit/post_test.rb:1010]:
"CurrentUser.post_update_count" didn't change by 1.
Expected: 1
  Actual: 3

app/models/post.rb

@@ -1436,6 +1436,8 @@ class Post < ActiveRecord::Base
 
     def create_new_version
       User.where(id: CurrentUser.id).update_all("post_update_count = post_update_count + 1")
+      CurrentUser.reload
+
       versions.create(
         :rating => rating,
         :source => source,