autotest: No such file or directory - -u (Errno::ENOENT)

Hi there,

I currently can not get autottest to run:

loading autotest/rails
/opt/local/bin/ruby -I.:lib:test -rubygems -e "%w[test/unit
test/functional/home_controller_test.rb
test/unit/helpers/home_helper_test.rb].each { |f| require f }" |
unit_diff -u
/opt/local/lib/ruby/gems/1.8/gems/ZenTest-4.1.4/lib/unit_diff.rb:70:in
`gets': No such file or directory - -u (Errno::ENOENT)
  from
/opt/local/lib/ruby/gems/1.8/gems/ZenTest-4.1.4/lib/unit_diff.rb:70:in
`parse_input'
  from
/opt/local/lib/ruby/gems/1.8/gems/ZenTest-4.1.4/lib/unit_diff.rb:182:in
`unit_diff'
  from
/opt/local/lib/ruby/gems/1.8/gems/ZenTest-4.1.4/lib/unit_diff.rb:56:in
`unit_diff'
  from /opt/local/lib/ruby/gems/1.8/gems/ZenTest-4.1.4/bin/unit_diff:37
  from /opt/local/bin/unit_diff:19:in `load'
  from /opt/local/bin/unit_diff:19
/opt/local/lib/ruby/1.8/test/unit/ui/console/testrunner.rb:108:in
`flush': Broken pipe (Errno::EPIPE)
  from /opt/local/lib/ruby/1.8/test/unit/ui/console/testrunner.rb:108:in
`output'
  from /opt/local/lib/ruby/1.8/test/unit/ui/console/testrunner.rb:51:in
`setup_mediator'
  from /opt/local/lib/ruby/1.8/test/unit/ui/console/testrunner.rb:39:in
`start'
  from /opt/local/lib/ruby/1.8/test/unit/ui/testrunnerutilities.rb:29:in
`run'
  from /opt/local/lib/ruby/1.8/test/unit/autorunner.rb:216:in `run'
  from /opt/local/lib/ruby/1.8/test/unit/autorunner.rb:12:in `run'
  from /opt/local/lib/ruby/1.8/test/unit.rb:278
  from -e:1

Envrionment:

ZenTest 4.1.4
MacOS Leopard
- RUBYGEMS VERSION: 1.3.5
- RUBY VERSION: 1.8.7 (2009-06-12 patchlevel 174) [i686-darwin9]

Anybody any idea what's wrong here?

Regards,
Johannes