Mongodb Moped 2.0.7未定义的方法`会话'；

我不知道这里发生了什么。 我升级到了MOPED2.0.7，我得到了这个未定义的方法“session”#

User.tags_index_collection
 => #<Moped::Collection:0x007fa744fe2c50 @database=#<Mongo::Database:0x70178196887520 name=my_mongo_development>, @name="users_tags_index"> 

但当我这么做的时候，我会

NoMethodError: undefined method `session' for #<Mongo::Database:0x007fa744fe2fc0>
    from /Users/me/.rvm/gems/ruby-2.3.0/gems/moped-2.0.7/lib/moped/query.rb:501:in `session'
    from /Users/me/.rvm/gems/ruby-2.3.0/gems/moped-2.0.7/lib/moped/query.rb:93:in `cursor'
    from /Users/me/.rvm/gems/ruby-2.3.0/gems/moped-2.0.7/lib/moped/query.rb:78:in `each'
    from (irb):8:in `entries'

NoMethodError:未定义的方法“session”#
User.tags_index_collection
 => #<Moped::Collection:0x007fa744fe2c50 @database=#<Mongo::Database:0x70178196887520 name=my_mongo_development>, @name="users_tags_index"> 

from/Users/me/.rvm/gems/ruby-2.3.0/gems/moped-2.0.7/lib/moped/query.rb:501:在“会话”中
from/Users/me/.rvm/gems/ruby-2.3.0/gems/moped-2.0.7/lib/moped/query.rb:93:in'cursor'
from/Users/me/.rvm/gems/ruby-2.3.0/gems/moped-2.0.7/lib/moped/query.rb:78:in'each'
发件人（irb）：8:在“条目”中

有什么想法吗