vendors/execa.js/checkMode
    function checkMode(stat, options) {
      var mod = stat.mode;
      var uid = stat.uid;
      var gid = stat.gid;
      var myUid = options.uid !== void 0 ? options.uid : process.getuid && process.getuid();
      var myGid = options.gid !== void 0 ? options.gid : process.getgid && process.getgid();
      var u = parseInt("100", 8);
      var g = parseInt("010", 8);
      var o = parseInt("001", 8);
      var ug = u | g;
      var ret = mod & o || mod & g && gid === myGid || mod & u && uid === myUid || mod & ug && myUid === 0;
      return ret;
    }