[PATCH] Finding records by ID and passing blank :condtions option throws ActiveRecord::StatementInvalid

When trying to find a record using an ID or an array of IDs, and a blank conditions options, an incorrect SQL statement is generated (for example

Person.find 1, :conditions => []

attempts to execute the following SQL:

SELECT * FROM person WHERE (person.id = 1 AND ())

which throws ActiveRecord::StatementInvalid.

This is in contrast to other find behaviour, for example:

Person.find :all, :conditions => []

which works as expected, and returns all records.

I have attached a patch that corrects this, with tests. This is my first Rails patch so any suggestions/criticisms welcome!

Thanks,
Dan