[typo] Problems running Typo edge

[Eamon Ford]

I've downloaded the Typo edge (revision 1485), but when I run "typo  
start ." in the directory, it gives me this:

  ** warning: web-server  unknown.  Use 'web-server=external' to  
disable.
/usr/local/lib/ruby/gems/1.8/gems/rails-app-installer-0.2.0/lib/rails- 
installer.rb:243:in `start': undefined method `start' for  
nil:NilClass (NoMethodError)
         from /usr/local/lib/ruby/gems/1.8/gems/rails-app- 
installer-0.2.0/lib/rails-installer/commands.rb:135:in `command'
         from /usr/local/lib/ruby/gems/1.8/gems/rails-app- 
installer-0.2.0/lib/rails-installer.rb:646:in `execute_command'
         from /usr/local/lib/ruby/gems/1.8/gems/typo-4.1.1/bin/typo:38
         from /usr/local/bin/typo:16:in `load'
         from /usr/local/bin/typo:16

Could anybody tell me how to fix this?

Thanks.