WDT Reset with demo application

I've got the latest master and have tried to flash my ESP8266 (actually a nodeMCU v0.9).

With the esptool.py provided, I get a 'Failed to connect' exception:

james@JAMES-DEB-PC:~/Downloads/esp-ginx$ make flash
make -C ./app flash
make[1]: Entering directory '/home/james/Downloads/esp-ginx/app'
../tools/esptool.py --port /dev/ttyUSB0 write_flash 0x00000 ../bin/0x00000.bin 0x10000 ../bin/0x10000.bin
Connecting...
Traceback (most recent call last):
  File "../tools/esptool.py", line 388, in <module>
    esp.connect()
  File "../tools/esptool.py", line 156, in connect
    raise Exception('Failed to connect')
Exception: Failed to connect
../Makefile:177: recipe for target 'flash' failed

If I replace the provided esptool.py with the latest from https://github.com/themadinventor/esptool, I can flash the ESP, but I get watchdog timer resets:

 ets Jan  8 2013,rst cause:4, boot mode:(3,6)

wdt reset
load 0x40100000, len 28428, room 16 
tail 12
chksum 0x82

I haven't changed anything in the esp-ginx repository besides the esptool.py file.

Do you think the esptool changes could cause the flash to be written incorrectly, causing WDT resets? I'm not skilled/knowledgeable enough to go through the changes and work out what could be wrong.

israellot / esp-ginx

WDT Reset with demo application #13