posts/show: avoid extra queries when rendering pool list.

app/models/pool.rb

@@ -39,9 +39,8 @@ class Pool < ApplicationRecord
     end
 
     def selected_first(current_pool_id)
-      return where("true") if current_pool_id.blank?
-      current_pool_id = current_pool_id.to_i
-      reorder(Arel.sql("(case pools.id when #{current_pool_id} then 0 else 1 end), pools.name"))
+      return all if current_pool_id.blank?
+      reorder(Arel.sql("(case pools.id when #{current_pool_id.to_i} then 0 else 1 end), pools.name"))
     end
 
     def name_matches(name)

app/views/posts/partials/show/_nav_links.html.erb

@@ -4,7 +4,7 @@
       <%= render "posts/partials/show/search_seq", :post => post %>
     <% end %>
 
-    <% if post.pools.undeleted.any? %>
+    <% if post.pools.undeleted.present? %>
       <%= render "posts/partials/show/pool_list", post: post, pools: post.pools.undeleted.selected_first(params[:pool_id]) %>
     <% end %>