BUGFIX: edit history on wiki posts should be visible

lib/guardian/post_guardian.rb

@@ -135,7 +135,10 @@ module PostGuardian
 
   def can_view_post_revisions?(post)
     return false unless post
-    return true if SiteSetting.edit_history_visible_to_public && !post.hidden
+
+    if !post.hidden
+      return true if post.wiki || SiteSetting.edit_history_visible_to_public
+    end
 
     authenticated? &&
     (is_staff? || @user.has_trust_level?(:elder) || @user.id == post.user_id) &&