mysql2 EINTR on connect error reproduction

test.rb

#!/usr/bin/env ruby

require 'mysql2'

trap("USR2") {}

pid = fork do
  loop do
    client = Mysql2::Client.new
    client.close
  end
end

until Process.waitpid(pid, Process::WNOHANG)
  Process.kill("USR2", pid)
  sleep 0.01
end
puts $?.to_s