Ruby » Ruby master

merge revision(s) 57415,57474: [Backport #13239]

    eval.c: copy special exception

    * eval.c (setup_exception): make unfrozen copy of special
      exception before setting up a cause.
    test_io.rb: separate a test

    * test/ruby/test_io.rb (test_closed_stream_in_rescue): run in a
      separated process.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@59538 b2dd03c8-39d4-4d8f-98ff-823fe69b080e