wiki excerpts: show alias/implication lists even for tags without a wiki.

app/logical/post_sets/post.rb

@@ -37,6 +37,11 @@ module PostSets
       end
     end
 
+    def tag
+      return nil if !is_single_tag?
+      @tag ||= Tag.find_by(name: Tag.normalize_name(tag_string))
+    end
+
     def has_artist?
       is_single_tag? && artist.present? && artist.visible?
     end

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

@@ -82,6 +82,8 @@
   <% else %>
     <% if post_set.tag_string.present? %>
       <p>There is currently no wiki page for the tag "<%= post_set.tag_string %>". You can <%= link_to "create one", new_wiki_page_path(:wiki_page => {:title => post_set.tag_string}) %>.</p>
+
+      <%= alias_and_implication_list(post_set.tag) %>
     <% end %>
   <% end %>
 </div>