buildr on ruby 1.9.1?

[Ittay Dror]

I've tried to install  buildr on top of ruby 1.9.1 (ruby gems 1.3.1) and
these are the errors i get:

<internal:gem_prelude>:249:in `push_gem_version_on_load_path': undefined
method `<=>' for nil:NilClass (NoMethodError)
   from <internal:gem_prelude>:14:in `gem'
   from /usr/bin/buildr-1.9:18:in `<main>'


Any help?

Ittay