has_many :through + scope + empty? fails in 2.3.2 (but not 2.3.0)

A Post has_many Tags through Taggings.

Tag has this named scope:

named_scope :by_name, { :order => 'name ASC' }

In Rails 2.2.2 and 2.3.0, this worked fine:

a_post.tags.by_name.empty?

It generates a query like

SELECT count(*) AS count_all FROM `tags` INNER JOIN `taggings` ON `tags`.id = `taggings`.tag_id WHERE ((`taggings`.post_id = 881129040)) 

In Rails 2.3.2, it breaks:

  SQL (0.0ms)   Mysql::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '*) AS count_tags_all FROM `tags` INNER JOIN `taggings` ON `tags`.id = `taggings`' at line 1: SELECT count(`tags`.*) AS count_tags_all FROM `tags` INNER JOIN `taggings` ON `tags`.id = `taggings`.tag_id WHERE (((`taggings`.post_id = 881129040)) AND ((`taggings`.post_id = 881129040))) 

The (invalid) query generated here is

SELECT count(`tags`.*) AS count_tags_all FROM `tags` INNER JOIN `taggings` ON `tags`.id = `taggings`.tag_id WHERE (((`taggings`.post_id = 881129040)) AND ((`taggings`.post_id = 881129040)))

I'm sorry I don't have more details or a failing spec yet. Figured I'd report the issue for now, and possibly dig into later.