make FileUtils tests safe when interrupting in setup
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36756 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
make FileUtils tests safe when interrupting in setup
do not assume cwd is TMPROOT and never remove current directory.
[ruby-core:47224][Bug #6884]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36756 b2dd03c8-39d4-4d8f-98ff-823fe69b080e