git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@54799 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
this fixes randomly test failure introduced by r54698.
cf. [Bug #12082]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@54799 b2dd03c8-39d4-4d8f-98ff-823fe69b080e