has_many associations and count

Hello core,

When using conditions from a variable, it can sometimes be an empty hash (at least in my projects). When using it with count on a ActiveRecord::Base:

User.count :conditions => {}
# => 3
But when working on a has_many association, this happens:

>> User.first.certificates.count :conditions => {}
ActiveRecord::StatementInvalid: Mysql::Error: #42000You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '))' at line 1: SELECT count(*) AS count_all FROM `certificates` WHERE (`certificates`.user_id = 442758120 AND ())

a patch to this bug can be found on http://rails.lighthouseapp.com/projects/8994/tickets/271-make-count-conditions-work-on-has_many-associations#ticket-271-1

Jan De Poorter