DateTime arithmetic: Stack level too deep

Do the following in a Rails 3.0.0.beta app (on ruby 1.8.7 at least)

script/rails console
DateTime.now - 1.day

Result:

SystemStackError: stack level too deep
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/core_ext/date_time/calculations.rb:52:in `advance'
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/core_ext/date_time/calculations.rb:52:in `advance'
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/duration.rb:90:in `sum'
from (irb):4:in `inject'
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/duration.rb:85:in `each'
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/duration.rb:85:in `inject'
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/duration.rb:85:in `sum'
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/duration.rb:61:in `since'
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/core_ext/date/calculations.rb:67:in `plus_with_duration'
from c:/ruby/lib/ruby/gems/1.8/gems/activesupport-3.0.0.beta/lib/active_support/core_ext/date/calculations.rb:77:in `-'
from (irb):4

Workaround: use to_i, then convert back to datetime. It's annoying though. Verified both on windows (mingw32 build) and mac OS