merge revision(s) 66618: [Backport #15660]
test_io.rb: increase timeout for RubyCI to stabilize AIX powerpc CI https://rubyci.org/logs/rubyci.s3.amazonaws.com/aix71_ppc/ruby-trunk/log/20181227T113302Z.fail.html.gz
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@67239 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 66618: [Backport #15660]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@67239 b2dd03c8-39d4-4d8f-98ff-823fe69b080e