Use native Errno mapping on Rubinius
Use native Errno mapping on Rubinius

dixiS/hiredis-rb,redis/hiredis-rb,ferdinandrosario/hiredis-rb,loggator/hiredis-rb,redis/hiredis-rb,ferdinandrosario/hiredis-rb,loggator/hiredis-rb,dixiS/hiredis-rb