Limit failing on Arel Rails 3.0Beta

I've been puzzled over this, maybe I misunderstood something about chaining and Arel, it could be an issue.

scenario::

There are 250 comments for this current_user, id=1

@comments= Comment.where("user_id =?, current_user).limit(10)

when performing this with Rails 3.0.0Bet
a, Ruby 1.9.1 I get a result set of 250 and the limit fails
checking the output with to_sql and is seems correct

e.g => "SELECT comments.* FROM comments WHERE (user_id =1) LIMIT 10"

but @comments.count comes up with 250 records.

with

@comments= Comment.find_by_sql("SELECT comments.* FROM comments WHERE (user_id =1) LIMIT 10") I get the expected 10 results...

I've searched all the tickets and cant seem to find any reference to this, I havent forked the latest beta3.0.1, and see no reference to this issue in the commits.