Udp Reentrancy Issue due to endPacketMayRetry() and scheduled functions

UdpReentrancyIssue. cpp

#include "Arduino.h"

WiFiUdp Udp;

Ticker pingAlive;

void pingAliveFunction() 
{
  Udp.beginPacket("watchdog.host.net", 12345);
  Udp.write("I'm still alive you dolt");
  Udp.endPacketMayRetry(); //retry if fail
} 

esp8266::polledTimeout::periodic checkGPIO(200);
int lastGPIO;

void setup() 
{
  WiFi.begin("blah", "bleh") ;
  while(WiFi.status() != connected) 
  {

  } 
  pingAlive.attach_scheduled(pingAliveFunction, 1000);
  pinMode(4, INPUT);
  lastGPIO = digitalRead(4);
} 



void loop() 
{

  if(WiFi. status() == connected && checkGPIO) 
  {
    int currGPIO = digitalRead(4);
    if(currGPIO != lastGPIO) 
    {
      lastGPIO = currGPIO;
      Udp.beginPacket("watchdog.host.net", 12345);
      Udp.write(String("gpio=") + currGPIO);
      Udp.endPacketMayRetry();
    } 
}