有谁见过这个错误吗?
irb(main):013:0> connection = Net::SSH.start( host , user , :password => password ) NameError: uninitialized constant Net::SSH::KnownHosts::SUPPORTED_TYPE from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:117:in `keys_for from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:105:in `each_line from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:105:in `keys_for from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:103:in `open from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:103:in `keys_for from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:33:in `search_in from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:33:in `map from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:33:in `search_in from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/known_hosts.rb:27:in `search_for from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/transport/algorithms.rb:237:in `prepare_preferred_algorithms! from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/transport/algorithms.rb:120:in `initialize from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/transport/session.rb:79:in `new from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh/transport/session.rb:79:in `initialize from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh.rb:186:in `new from /usr/lib/ruby/gems/1.8/gems/net-ssh-2.5.1/lib/net/ssh.rb:186:in `start from (irb):13 from /usr/lib/ruby/site_ruby/1.8/rubygems/specification.rb:1313