ESP8266.ping does not work as expected

also works for me with sdk 1.5.4

>require("ESP8266").getState();
={
  "sdkVersion": "1.5.4(baaeaebb)",
  "cpuFrequency": 160, "freeHeap": 9144, "maxCon": 10,
  "flashMap": "4MB:512/512",
  "flashKB": 4096,
  "flashChip": "0xe0 0x4016"
 }
>var ESP8266=require("ESP8266");
=function () { [native code] }
>var Wifi = require("Wifi")
=function () { [native code] }
>Wifi.getIP();
={
  "ip": "192.168.194.64",
  "netmask": "255.255.255.0",
  "gw": "192.168.194.1",
  "mac": "5c:cf:7f:05:c1:00"
 }
>ESP8266.setLog(2);
=undefined
>ESP8266.ping("192.168.2.1", function(e){ console.log(e);});
=undefined
>140681> Received a ping response!
{ "totalCount": 0, "totalBytes": 0, "totalTime": 0, "respTime": 5,
  "seqNo": 1, "timeoutCount": 0, "bytes": 32, "error": 0 }
>141775> Received a ping response!
{ "totalCount": 0, "totalBytes": 0, "totalTime": 0, "respTime": 2,
  "seqNo": 2, "timeoutCount": 0, "bytes": 32, "error": 0 }
>142824> Received a ping response!
{ "totalCount": 0, "totalBytes": 0, "totalTime": 0, "respTime": 1,
  "seqNo": 3, "timeoutCount": 0, "bytes": 32, "error": 0 }
>144024> Received a ping response!
{ "totalCount": 0, "totalBytes": 0, "totalTime": 0, "respTime": 1,
  "seqNo": 4, "timeoutCount": 0, "bytes": 32, "error": 0 }
>145149> Received a ping response!
{ "totalCount": 0, "totalBytes": 0, "totalTime": 0, "respTime": 1,
  "seqNo": 5, "timeoutCount": 0, "bytes": 32, "error": 0 }
>146322> ping 5, timeout 0, total payload 160 bytes, 5646 ms