Ruby

marshaltestlib.rb: use clean object for exception

• test/ruby/marshaltestlib.rb (test_exception): use separate
  clean object to raise an exception. TestCase instance often has
  modules included.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63134 b2dd03c8-39d4-4d8f-98ff-823fe69b080e