Fix #4159: Add pool history to post show pages.

app/views/pool_versions/index.html.erb

@@ -2,7 +2,7 @@
   <div id="a-index">
     <h1>Pool History</h1>
 
-    <% if params.dig(:search, :pool_id).present? %>
+    <% if params.dig(:search, :pool_id).present? || params.dig(:search, :post_id).present? %>
       <%= render "revert_listing" %>
     <% else %>
       <%= render "standard_listing" %>

app/views/posts/show.html.erb

@@ -28,6 +28,7 @@
         <h1>History</h1>
         <ul>
           <li><%= link_to "Tags", post_versions_path(search: { post_id: @post.id }) %></li>
+          <li><%= link_to "Pools", pool_versions_path(search: { post_id: @post.id }) %></li>
           <li><%= link_to "Notes", note_versions_path(search: { post_id: @post.id }) %></li>
           <li><%= link_to "Moderation", post_events_path(@post.id) %></li>
           <li><%= link_to "Commentary", artist_commentary_versions_path(search: { post_id: @post.id }) %></li>