I am running 2.0-alpha.9507 on OS X 10.9.1.

I first noticed this problem in the rails bundle whenever it requests to
create a new file.

I can recreate the issue with the following code:

require '/Users/curt/Library/Application Support/TextMate/Managed/Bundles/Bundle Support.tmbundle/Support/shared/lib/ui.rb'

TextMate::UI.request_confirmation(
  :button1 => "Create",
  :button2 => "Cancel",
  :title => "Missing foo.rb",
  :prompt => "Create missing foo.rb?"
)

Pressing Cmd-R results in:
ArgumentError: An object in the argument tree could not be converted

Here is the stack trace:
/Users/curt/Library/Application Support/TextMate/Managed/Bundles/Bundle Support.tmbundle/Support/shared/lib/ui.rb:54:in `to_plist': An object in the argument tree could not be converted (ArgumentError)
    from /Users/curt/Library/Application Support/TextMate/Managed/Bundles/Bundle Support.tmbundle/Support/shared/lib/ui.rb:54:in `alert'
    from /Users/curt/Library/Application Support/TextMate/Managed/Bundles/Bundle Support.tmbundle/Support/shared/lib/ui.rb:277:in `request_confirmation'

It is runing ruby version:  2.0.0-p247

Is this a known problem.  Or perhaps a problem using Ruby 2.0?