If it helps:
in ESP8266 ver. 2.0.0 was added abort in
here
cores/esp8266/core_esp8266_postmortem.c:
void abort() __attribute__((noreturn));
void abort(){
// cause exception
s_abort_called = true;
do {
*((int*)0) = 0;
} while(true);
}
i comment the lines in MySensors/core/MyMainESP8266.cpp and it compiled ok.