posts/index: update pending BUR notice criteria.

* Only show pending BUR notice on first page.
* Show pending BUR notice for all searches that include a single tag.

app/logical/post_sets/post.rb

@@ -132,8 +132,8 @@ module PostSets
     end
 
     def pending_bulk_update_requests
-      return BulkUpdateRequest.none unless query.is_simple_tag?
-      @pending_bulk_update_requests ||= BulkUpdateRequest.pending.where_array_includes_any(:tags, query.tags.first.name)
+      return BulkUpdateRequest.none unless tag.present?
+      @pending_bulk_update_requests ||= BulkUpdateRequest.pending.where_array_includes_any(:tags, tag.name)
     end
   end
 end

app/views/posts/partials/index/_posts.html.erb

@@ -19,7 +19,7 @@
     </div>
   <% end %>
 
-  <% if CurrentUser.user.is_member? && post_set.query.is_simple_tag? %>
+  <% if CurrentUser.user.is_member? && post_set.tag.present? && post_set.current_page == 1 %>
     <% cache("tag-change-notice:#{post_set.query.normalize_query}", expires_in: 4.hours) do %>
       <% if post_set.pending_bulk_update_requests.present? %>
         <div class="fineprint tag-change-notice">