Problem with rio-0.3.4

Running this script (named riotest) with rio-0.3.3:

require ‘rubygems’
require ‘rio’
puts rio(‘riotest’).readlines

correctly says:

wybo>ruby riotest
require ‘rubygems’
require ‘rio’
puts rio(‘riotest’).readlines

But with rio-0.3.4 I get:

wybo>ruby riotest
…/gems/1.8/gems/rio-0.3.4/lib/rio/ops/file.rb:62:
uninitialized constant rio::ops::fileordir::existornot (nameerror)
from … /site_ruby/1.8/rubygems/custom_require.rb:21:
in require' from ... /gems/1.8/gems/rio-0.3.4/lib/rio/file.rb:39 from ... /site_ruby/1.8/rubygems/custom_require.rb:21: inrequire’
from … /gems/1.8/gems/rio-0.3.4/lib/rio/factory.rb:197:
in state2class' from ... /gems/1.8/gems/rio-0.3.4/lib/rio/factory.rb:206: intry_state_proc’
from … /gems/1.8/gems/rio-0.3.4/lib/rio/state.rb:120:
in become' from ... /gems/1.8/gems/rio-0.3.4/lib/rio/path.rb:80: inefile’
from … /gems/1.8/gems/rio-0.3.4/lib/rio/path.rb:65:
in when_missing' from ... /gems/1.8/gems/rio-0.3.4/lib/rio/state.rb:134: inmethod_missing’
from … /gems/1.8/gems/rio-0.3.4/lib/rio/state.rb:136:
in method_missing' from ... /gems/1.8/gems/rio-0.3.4/lib/rio/if/stream.rb:188: inreadlines’
from riotest:3
wybo>
(I tweaked the output a little for clarity)

Any ideas?