I can't get the autoproj_bootstrap script to run in Ubuntu hardy:

$ ruby --version
ruby 1.8.6 (2007-09-24 patchlevel 111) [i486-linux]

First error was:
$ ruby autoproj_bootstrap
/usr/lib/ruby/1.8/rubygems/source_index.rb:92:in `load_specification':
private method `specification_version=' called for
#<Gem::Specification:0xb7cd3f7c> (NoMethodError)
from /usr/lib/ruby/1.8/rubygems/specification.rb:421:in `initialize'
from (eval):3:in `new'
from (eval):3:in `load_specification'
from /usr/lib/ruby/1.8/rubygems/source_index.rb:128:in `eval'
from /usr/lib/ruby/1.8/rubygems/source_index.rb:92:in
`load_specification'
from /usr/lib/ruby/1.8/rubygems/source_index.rb:128:in `load_gems_in'
from /usr/lib/ruby/1.8/rubygems/source_index.rb:127:in `each'
from /usr/lib/ruby/1.8/rubygems/source_index.rb:127:in `load_gems_in'
... 13 levels...
from /usr/lib/ruby/1.8/tempfile.rb:8
from /usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require'
from /usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `require'
from autoproj_bootstrap:41

I could just remove the require 'tempfile' line. But then I got:

$ ruby autoproj_bootstrap
autoproj: installing autoproj and its dependencies (this can take a long time)
autoproj_bootstrap:93:in `operating_system': wrong argument type
Symbol (expected Proc) (TypeError)
from autoproj_bootstrap:122:in `generate_os_script'
from autoproj_bootstrap:210:in `install'
from autoproj_bootstrap:318

Any clues on what the root cause is here ?

Peter