mongoid/mongoid — pull request #1659 by gerad (2012-01-30 22:44:17+00:00)
Title: setting an embeds many association a second time does not persist the relationship 

here's an example

~~~ruby
person = Person.create addresses: [address_one]
person.address = [address_two]
person.save
person.reload.addresses.first # => address_one
~~~

The pull request has a failing spec, but would appreciate any help on figuring out where to make the fix.

It's somewhere around persisting an embeds many relationship.