* Avoids the thread-safety issues mentioned in r61192,
  when thread concurrently modify default Encodings or $VERBOSE.
  Their state will always be the original one once the test finishes.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61195 b2dd03c8-39d4-4d8f-98ff-823fe69b080e