merge revision(s) 61500: [Backport #14248]
fix fd mask detection on os x This was broken in r59440 (3215b27a9abd8de793cf517f32d8901fd421eb1c) [Bug #14248] From: Stefan Kaes <skaes@railsexpress.de>
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@61582 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 61500: [Backport #14248]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@61582 b2dd03c8-39d4-4d8f-98ff-823fe69b080e