Don't allow new users to remove tags

fixes #2427

app/models/post.rb

@@ -488,7 +488,8 @@ class Post < ActiveRecord::Base
     def update_tag_post_counts
       decrement_tags = tag_array_was - tag_array
 
-      if decrement_tags.size > 1 && !CurrentUser.is_builder? && CurrentUser.created_at > 1.week.ago
+      decrement_tags_except_requests = decrement_tags.reject {|tag| tag == "tagme" || tag.end_with?("_request")}
+      if decrement_tags_except_requests.size > 0 && !CurrentUser.is_builder? && CurrentUser.created_at > 1.week.ago
         self.errors.add(:updater_id, "must have an account at least 1 week old to remove tags")
         return false
       end

test/unit/post_test.rb

@@ -463,14 +463,20 @@ class PostTest < ActiveSupport::TestCase
 
       context "as a new user" do
         setup do
-          @post.update_attribute(:tag_string, "aaa bbb ccc ddd")
+          @post.update_attribute(:tag_string, "aaa bbb ccc ddd tagme")
           CurrentUser.user = FactoryGirl.create(:user)
         end
 
-        should "not allow you to remove more than 2 tags" do
+        should "not allow you to remove tags" do
           @post.update_attributes(:tag_string => "aaa")
           assert_equal(["You must have an account at least 1 week old to remove tags"], @post.errors.full_messages)
         end
+
+        should "allow you to remove request tags" do
+          @post.update_attributes(:tag_string => "aaa bbb ccc ddd")
+          @post.reload
+          assert_equal("aaa bbb ccc ddd", @post.tag_string)
+        end
       end
 
       context "with a banned artist" do