In release 1.3 I've patches uboot in a way similar to the one used by @arbor: you need to type "ard" to enter uboot console, otherwise linux will start ("ard" is the same sequence used on the Arduino Tre)
Can you double check if this works?
@Jantje, you may also want to uncomment reset-mcu in /etc/rc.local (also in the new image)