Collection read preference not passed to find command

irb(main):006:0> c=a['test']

=> #<Mongo::Collection:0x47405477702640 namespace=admin.test>

irb(main):007:0> c.read_preference

=> {"mode"=>:secondary}

irb(main):008:0> d=c.with(read:{mode: :primary})

=> #<Mongo::Collection:0x47405477816800 namespace=admin.test>

irb(main):009:0> d.read_preference

=> {:mode=>:primary}

irb(main):010:0> d.find.to_a.count

...

D, [2019-06-24T18:00:36.726737 #21320] DEBUG -- : MONGODB | localhost:27741 | admin.find | STARTED | {"find"=>"test", "filter"=>{}, "$readPreference"=>{"mode"=>"secondary"}, "lsid"=>{"id"=><BSON::Binary:0x47405477895640 type=uuid data=0x67aab09b8aa14b73...>}}