When implementing delete_on on the swift driver, kaitlin.mahar@10gen.com saw errors about collation on mongoc_collection_delete_one. After investigating it looks like collation isn't being sent for delete_one and delete_many in master.

It looks like it also effects pre-IDL changes, but in a different way. Based on the server error, it looks like pre-IDL changes we're sending collation but as a command option, not an option inside the deletes array (https://docs.mongodb.com/manual/reference/command/delete/). I do not think this affects pre-1.9 since delete_one and delete_many were introduced in 1.9.