Merge pull request #67 from ruby/fix-bundle-exec-rake

Fixes "bundle exec rake" clash with test/unit

Author: hsbt

Rakefile

@@ -3,7 +3,7 @@ require "rake/testtask"
 
 Rake::TestTask.new(:test) do |t|
   t.libs << "test/lib"
-  t.ruby_opts << "-rhelper"
+  t.ruby_opts << "-rbundler/setup -rhelper"
   t.test_files = FileList["test/**/test_*.rb"]
 end