Capistrano Multistage error

humansky@cluedo:~/workspace/wordpress$ cap uname
    triggering start callbacks for `uname'
  * executing `multistage:ensure'
*** Defaulting to `staging'
  * executing `staging'
  * executing `uname'
  * executing "uname -a"
    servers: ["blogs-dev.princeton.edu"]
    [blogs-dev.princeton.edu] executing command
 ** [out :: blogs-dev.princeton.edu] Linux blogs-dev.Princeton.EDU 2.6.18-238.19.1.0.1.el5 #1 SMP Fri Jul 15 03:53:42 EDT 2011 i686 i686 i386 GNU/Linux
    command finished
humansky@cluedo:~/workspace/wordpress$ cap deploy
    triggering start callbacks for `deploy'
  * executing `multistage:ensure'
*** Defaulting to `staging'
  * executing `staging'
  * executing `deploy'
  * executing `deploy:update'
 ** transaction: start
  * executing `deploy:update_code'
    updating the cached checkout on all servers
    executing locally: "git ls-remote git@git.princeton.edu:wordpress.git master"
/usr/bin/git
*** [deploy:update_code] rolling back
  * executing "rm -rf /var/local/www/wordpress/releases/20110815185709; true"
    servers: ["blogs-dev.princeton.edu"]
    [blogs-dev.princeton.edu] executing command
    command finished
/var/lib/gems/1.8/gems/capistrano-2.8.0/lib/capistrano/recipes/deploy/scm/git.rb:158:in `checkout': undefined method `compact' for #<String:0xb70bd6d4> (NoMethodError)
    from /var/lib/gems/1.8/gems/capistrano-2.8.0/lib/capistrano/recipes/deploy/strategy/remote_cache.rb:36:in `update_repository_cache'
    from /var/lib/gems/1.8/gems/capistrano-2.8.0/lib/capistrano/recipes/deploy/strategy/remote_cache.rb:15:in `deploy!'
    from /usr/lib/ruby/1.8/capistrano/recipes/deploy.rb:213:in `load'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:139:in `instance_eval'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:139:in `invoke_task_directly_without_callbacks'
    from /usr/lib/ruby/1.8/capistrano/configuration/callbacks.rb:27:in `invoke_task_directly'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:89:in `execute_task'
    from /usr/lib/ruby/1.8/capistrano/configuration/namespaces.rb:186:in `send'
    from /usr/lib/ruby/1.8/capistrano/configuration/namespaces.rb:186:in `method_missing'
    from /usr/lib/ruby/1.8/capistrano/configuration/namespaces.rb:104:in `update_code'
    from /usr/lib/ruby/1.8/capistrano/recipes/deploy.rb:194:in `load'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:56:in `transaction'
    from /usr/lib/ruby/1.8/capistrano/configuration/namespaces.rb:186:in `send'
    from /usr/lib/ruby/1.8/capistrano/configuration/namespaces.rb:186:in `method_missing'
    from /usr/lib/ruby/1.8/capistrano/recipes/deploy.rb:193:in `load'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:139:in `instance_eval'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:139:in `invoke_task_directly_without_callbacks'
    from /usr/lib/ruby/1.8/capistrano/configuration/callbacks.rb:27:in `invoke_task_directly'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:89:in `execute_task'
    from /usr/lib/ruby/1.8/capistrano/configuration/namespaces.rb:186:in `send'
    from /usr/lib/ruby/1.8/capistrano/configuration/namespaces.rb:186:in `method_missing'
    from /usr/lib/ruby/1.8/capistrano/configuration/namespaces.rb:104:in `update'
    from /usr/lib/ruby/1.8/capistrano/recipes/deploy.rb:162:in `load'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:139:in `instance_eval'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:139:in `invoke_task_directly_without_callbacks'
    from /usr/lib/ruby/1.8/capistrano/configuration/callbacks.rb:27:in `invoke_task_directly'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:89:in `execute_task'
    from /usr/lib/ruby/1.8/capistrano/configuration/execution.rb:101:in `find_and_execute_task'
    from /usr/lib/ruby/1.8/capistrano/cli/execute.rb:45:in `execute_requested_actions_without_help'
    from /usr/lib/ruby/1.8/capistrano/cli/execute.rb:44:in `each'
    from /usr/lib/ruby/1.8/capistrano/cli/execute.rb:44:in `execute_requested_actions_without_help'
    from /usr/lib/ruby/1.8/capistrano/cli/help.rb:19:in `execute_requested_actions'
    from /usr/lib/ruby/1.8/capistrano/cli/execute.rb:33:in `execute!'
    from /usr/lib/ruby/1.8/capistrano/cli/execute.rb:14:in `execute'
    from /usr/bin/cap:4
humansky@cluedo:~/workspace/wordpress$