MRI 的 BUG,等 2.4.1
https://bugs.ruby-lang.org/issues/13107
wrong argument type Integer (expected Proc)
/usr/local/lib/ruby/2.4.0/forwardable.rb:228:in `database'
/server/vendor/bundle/ruby/2.4.0/gems/mongo-2.4.1/lib/mongo/cursor/builder/kill_cursors_command.rb:51:in `specification'
/server/vendor/bundle/ruby/2.4.0/gems/mongo-2.4.1/lib/mongo/cursor.rb:217:in `kill_cursors_op_spec'
/server/vendor/bundle/ruby/2.4.0/gems/mongo-2.4.1/lib/mongo/cursor.rb:64:in `initialize'
/server/vendor/bundle/ruby/2.4.0/gems/mongo-2.4.1/lib/mongo/collection/view/iterable.rb:42:in `new'
/server/vendor/bundle/ruby/2.4.0/gems/mongo-2.4.1/lib/mongo/collection/view/iterable.rb:42:in `block in each'
/server/vendor/bundle/ruby/2.4.0/gems/mongo-2.4.1/lib/mongo/retryable.rb:51:in `read_with_retry'
/server/vendor/bundle/ruby/2.4.0/gems/mongo-2.4.1/lib/mongo/collection/view/iterable.rb:39:in `each'
/server/vendor/bundle/ruby/2.4.0/gems/mongoid-6.0.3/lib/mongoid/query_cache.rb:222:in `each'
/server/vendor/bundle/ruby/2.4.0/gems/mongoid-6.0.3/lib/mongoid/contextual/mongo.rb:430:in `reduce'
/server/vendor/bundle/ruby/2.4.0/gems/mongoid-6.0.3/lib/mongoid/contextual/mongo.rb:430:in `pluck'
/server/vendor/bundle/ruby/2.4.0/gems/mongoid-6.0.3/lib/mongoid/contextual.rb:20:in `pluck'
/server/vendor/bundle/ruby/2.4.0/gems/mongoid-6.0.3/lib/mongoid/findable.rb:15:in `pluck'